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.\" Automatically generated by Pod::Man 2.25 (Pod::Simple 3.20) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. Capital omega is used to do unbreakable dashes and .\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff, .\" nothing in troff, for use with C<>. .tr \(*W- .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' .ie n \{\ . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} .el\{\ . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is turned on, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. 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No user-serviceable parts. . \" fudge factors for nroff and troff .if n \{\ . ds #H 0 . ds #V .8m . ds #F .3m . ds #[ \f1 . ds #] \fP .\} .if t \{\ . ds #H ((1u-(\\\\n(.fu%2u))*.13m) . ds #V .6m . ds #F 0 . ds #[ \& . ds #] \& .\} . \" simple accents for nroff and troff .if n \{\ . ds ' \& . ds ` \& . ds ^ \& . ds , \& . ds ~ ~ . ds / .\} .if t \{\ . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' .\} . \" troff and (daisy-wheel) nroff accents .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' .ds 8 \h'\*(#H'\(*b\h'-\*(#H' .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] .ds ae a\h'-(\w'a'u*4/10)'e .ds Ae A\h'-(\w'A'u*4/10)'E . \" corrections for vroff .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' . \" for low resolution devices (crt and lpr) .if \n(.H>23 .if \n(.V>19 \ \{\ . ds : e . ds 8 ss . ds o a . ds d- d\h'-1'\(ga . ds D- D\h'-1'\(hy . ds th \o'bp' . ds Th \o'LP' . ds ae ae . ds Ae AE .\} .rm #[ #] #H #V #F C .\" ======================================================================== .\" .IX Title "DBD::SQLite 3" .TH DBD::SQLite 3 "2012-06-09" "perl v5.16.3" "User Contributed Perl Documentation" .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" DBD::SQLite \- Self\-contained RDBMS in a DBI Driver .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 2 \& use DBI; \& my $dbh = DBI\->connect("dbi:SQLite:dbname=$dbfile","",""); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" SQLite is a public domain file-based relational database engine that you can find at <http://www.sqlite.org/>. .PP \&\fBDBD::SQLite\fR is a Perl \s-1DBI\s0 driver for SQLite, that includes the entire thing in the distribution. So in order to get a fast transaction capable \s-1RDBMS\s0 working for your perl project you simply have to install this module, and \fBnothing\fR else. .PP SQLite supports the following features: .IP "Implements a large subset of \s-1SQL92\s0" 4 .IX Item "Implements a large subset of SQL92" See <http://www.sqlite.org/lang.html> for details. .IP "A complete \s-1DB\s0 in a single disk file" 4 .IX Item "A complete DB in a single disk file" Everything for your database is stored in a single disk file, making it easier to move things around than with \s-1DBD::CSV\s0. .IP "Atomic commit and rollback" 4 .IX Item "Atomic commit and rollback" Yes, \fBDBD::SQLite\fR is small and light, but it supports full transactions! .IP "Extensible" 4 .IX Item "Extensible" User-defined aggregate or regular functions can be registered with the \&\s-1SQL\s0 parser. .PP There's lots more to it, so please refer to the docs on the SQLite web page, listed above, for \s-1SQL\s0 details. Also refer to \s-1DBI\s0 for details on how to use \s-1DBI\s0 itself. The \s-1API\s0 works like every \s-1DBI\s0 module does. However, currently many statement attributes are not implemented or are limited by the typeless nature of the SQLite database. .SH "NOTABLE DIFFERENCES FROM OTHER DRIVERS" .IX Header "NOTABLE DIFFERENCES FROM OTHER DRIVERS" .SS "Database Name Is A File Name" .IX Subsection "Database Name Is A File Name" SQLite creates a file per a database. You should pass the \f(CW\*(C`path\*(C'\fR of the database file (with or without a parent directory) in the \s-1DBI\s0 connection string (as a database \f(CW\*(C`name\*(C'\fR): .PP .Vb 1 \& my $dbh = DBI\->connect("dbi:SQLite:dbname=$dbfile","",""); .Ve .PP The file is opened in read/write mode, and will be created if it does not exist yet. .PP Although the database is stored in a single file, the directory containing the database file must be writable by SQLite because the library will create several temporary files there. .PP If the filename \f(CW$dbfile\fR is \*(L":memory:\*(R", then a private, temporary in-memory database is created for the connection. This in-memory database will vanish when the database connection is closed. It is handy for your library tests. .PP Note that future versions of SQLite might make use of additional special filenames that begin with the \*(L":\*(R" character. It is recommended that when a database filename actually does begin with a \*(L":\*(R" character you should prefix the filename with a pathname such as \*(L"./\*(R" to avoid ambiguity. .PP If the filename \f(CW$dbfile\fR is an empty string, then a private, temporary on-disk database will be created. This private database will be automatically deleted as soon as the database connection is closed. .SS "Accessing A Database With Other Tools" .IX Subsection "Accessing A Database With Other Tools" To access the database from the command line, try using \f(CW\*(C`dbish\*(C'\fR which comes with the DBI::Shell module. Just type: .PP .Vb 1 \& dbish dbi:SQLite:foo.db .Ve .PP On the command line to access the file \fIfoo.db\fR. .PP Alternatively you can install SQLite from the link above without conflicting with \fBDBD::SQLite\fR and use the supplied \f(CW\*(C`sqlite3\*(C'\fR command line tool. .SS "Blobs" .IX Subsection "Blobs" As of version 1.11, blobs should \*(L"just work\*(R" in SQLite as text columns. However this will cause the data to be treated as a string, so \s-1SQL\s0 statements such as length(x) will return the length of the column as a \s-1NUL\s0 terminated string, rather than the size of the blob in bytes. In order to store natively as a \s-1BLOB\s0 use the following code: .PP .Vb 2 \& use DBI qw(:sql_types); \& my $dbh = DBI\->connect("dbi:SQLite:dbfile","",""); \& \& my $blob = \`cat foo.jpg\`; \& my $sth = $dbh\->prepare("INSERT INTO mytable VALUES (1, ?)"); \& $sth\->bind_param(1, $blob, SQL_BLOB); \& $sth\->execute(); .Ve .PP And then retrieval just works: .PP .Vb 4 \& $sth = $dbh\->prepare("SELECT * FROM mytable WHERE id = 1"); \& $sth\->execute(); \& my $row = $sth\->fetch; \& my $blobo = $row\->[1]; \& \& # now $blobo == $blob .Ve .SS "Functions And Bind Parameters" .IX Subsection "Functions And Bind Parameters" As of this writing, a \s-1SQL\s0 that compares a return value of a function with a numeric bind value like this doesn't work as you might expect. .PP .Vb 4 \& my $sth = $dbh\->prepare(q{ \& SELECT bar FROM foo GROUP BY bar HAVING count(*) > ?; \& }); \& $sth\->execute(5); .Ve .PP This is because DBD::SQLite assumes that all the bind values are text (and should be quoted) by default. Thus the above statement becomes like this while executing: .PP .Vb 1 \& SELECT bar FROM foo GROUP BY bar HAVING count(*) > "5"; .Ve .PP There are three workarounds for this. .IP "Use \fIbind_param()\fR explicitly" 4 .IX Item "Use bind_param() explicitly" As shown above in the \f(CW\*(C`BLOB\*(C'\fR section, you can always use \&\f(CW\*(C`bind_param()\*(C'\fR to tell the type of a bind value. .Sp .Vb 1 \& use DBI qw(:sql_types); # Don\*(Aqt forget this \& \& my $sth = $dbh\->prepare(q{ \& SELECT bar FROM foo GROUP BY bar HAVING count(*) > ?; \& }); \& $sth\->bind_param(1, 5, SQL_INTEGER); \& $sth\->execute(); .Ve .IP "Add zero to make it a number" 4 .IX Item "Add zero to make it a number" This is somewhat weird, but works anyway. .Sp .Vb 4 \& my $sth = $dbh\->prepare(q{ \& SELECT bar FROM foo GROUP BY bar HAVING count(*) > (? + 0); \& }); \& $sth\->execute(5); .Ve .ie n .IP "Set ""sqlite_see_if_its_a_number"" database handle attribute" 4 .el .IP "Set \f(CWsqlite_see_if_its_a_number\fR database handle attribute" 4 .IX Item "Set sqlite_see_if_its_a_number database handle attribute" As of version 1.32_02, you can use \f(CW\*(C`sqlite_see_if_its_a_number\*(C'\fR to let DBD::SQLite to see if the bind values are numbers or not. .Sp .Vb 5 \& $dbh\->{sqlite_see_if_its_a_number} = 1; \& my $sth = $dbh\->prepare(q{ \& SELECT bar FROM foo GROUP BY bar HAVING count(*) > ?; \& }); \& $sth\->execute(5); .Ve .Sp You can set it to true when you connect to a database. .Sp .Vb 5 \& my $dbh = DBI\->connect(\*(Aqdbi:SQLite:foo\*(Aq, undef, undef, { \& AutoCommit => 1, \& RaiseError => 1, \& sqlite_see_if_its_a_number => 1, \& }); .Ve .Sp This is the most straightforward solution, but as noted above, existing data in your databases created by DBD::SQLite have not always been stored as numbers, so this *might* cause other obscure problems. Use this sparingly when you handle existing databases. If you handle databases created by other tools like native \f(CW\*(C`sqlite3\*(C'\fR command line tool, this attribute would help you. .SS "Placeholders" .IX Subsection "Placeholders" SQLite supports several placeholder expressions, including \f(CW\*(C`?\*(C'\fR and \f(CW\*(C`:AAAA\*(C'\fR. Consult the \s-1DBI\s0 and sqlite documentation for details. .PP <http://www.sqlite.org/lang_expr.html#varparam> .PP Note that a question mark actually means a next unused (numbered) placeholder. You're advised not to use it with other (numbered or named) placeholders to avoid confusion. .PP .Vb 4 \& my $sth = $dbh\->prepare( \& \*(Aqupdate TABLE set a=?1 where b=?2 and a IS NOT ?1\*(Aq \& ); \& $sth\->execute(1, 2); .Ve .SS "Foreign Keys" .IX Subsection "Foreign Keys" \&\fB\s-1BE\s0 \s-1PREPARED\s0! \s-1WOLVES\s0 \s-1APPROACH\s0!!\fR .PP SQLite has started supporting foreign key constraints since 3.6.19 (released on Oct 14, 2009; bundled in DBD::SQLite 1.26_05). To be exact, SQLite has long been able to parse a schema with foreign keys, but the constraints has not been enforced. Now you can issue a pragma actually to enable this feature and enforce the constraints. .PP To do this, issue the following pragma (see below), preferably as soon as you connect to a database and you're not in a transaction: .PP .Vb 1 \& $dbh\->do("PRAGMA foreign_keys = ON"); .Ve .PP And you can explicitly disable the feature whenever you like by turning the pragma off: .PP .Vb 1 \& $dbh\->do("PRAGMA foreign_keys = OFF"); .Ve .PP As of this writing, this feature is disabled by default by the sqlite team, and by us, to secure backward compatibility, as this feature may break your applications, and actually broke some for us. If you have used a schema with foreign key constraints but haven't cared them much and supposed they're always ignored for SQLite, be prepared, and \fBplease do extensive testing to ensure that your applications will continue to work when the foreign keys support is enabled by default\fR. It is very likely that the sqlite team will turn it default-on in the future, and we plan to do it \&\s-1NO\s0 \s-1LATER\s0 \s-1THAN\s0 they do so. .PP See <http://www.sqlite.org/foreignkeys.html> for details. .SS "Pragma" .IX Subsection "Pragma" SQLite has a set of \*(L"Pragma\*(R"s to modifiy its operation or to query for its internal data. These are specific to SQLite and are not likely to work with other \s-1DBD\s0 libraries, but you may find some of these are quite useful. DBD::SQLite actually sets some (like \&\f(CW\*(C`show_datatypes\*(C'\fR) for you when you connect to a database. See <http://www.sqlite.org/pragma.html> for details. .SS "Transactions" .IX Subsection "Transactions" DBI/DBD::SQLite's transactions may be a bit confusing. They behave differently according to the status of the \f(CW\*(C`AutoCommit\*(C'\fR flag: .IP "When the AutoCommit flag is on" 4 .IX Item "When the AutoCommit flag is on" You're supposed to always use the auto-commit mode, except you explicitly begin a transaction, and when the transaction ended, you're supposed to go back to the auto-commit mode. To begin a transaction, call \f(CW\*(C`begin_work\*(C'\fR method, or issue a \f(CW\*(C`BEGIN\*(C'\fR statement. To end it, call \f(CW\*(C`commit/rollback\*(C'\fR methods, or issue the corresponding statements. .Sp .Vb 1 \& $dbh\->{AutoCommit} = 1; \& \& $dbh\->begin_work; # or $dbh\->do(\*(AqBEGIN TRANSACTION\*(Aq); \& \& # $dbh\->{AutoCommit} is turned off temporarily during a transaction; \& \& $dbh\->commit; # or $dbh\->do(\*(AqCOMMIT\*(Aq); \& \& # $dbh\->{AutoCommit} is turned on again; .Ve .IP "When the AutoCommit flag is off" 4 .IX Item "When the AutoCommit flag is off" You're supposed to always use the transactional mode, until you explicitly turn on the AutoCommit flag. You can explicitly issue a \f(CW\*(C`BEGIN\*(C'\fR statement (only when an actual transaction has not begun yet) but you're not allowed to call \f(CW\*(C`begin_work\*(C'\fR method (if you don't issue a \f(CW\*(C`BEGIN\*(C'\fR, it will be issued internally). You can commit or roll it back freely. Another transaction will automatically begins if you execute another statement. .Sp .Vb 1 \& $dbh\->{AutoCommit} = 0; \& \& # $dbh\->do(\*(AqBEGIN TRANSACTION\*(Aq) is not necessary, but possible \& \& ... \& \& $dbh\->commit; # or $dbh\->do(\*(AqCOMMIT\*(Aq); \& \& # $dbh\->{AutoCommit} stays intact; \& \& $dbh\->{AutoCommit} = 1; # ends the transactional mode .Ve .PP This \f(CW\*(C`AutoCommit\*(C'\fR mode is independent from the autocommit mode of the internal SQLite library, which always begins by a \f(CW\*(C`BEGIN\*(C'\fR statement, and ends by a \f(CW\*(C`COMMIT\*(C'\fR or a <\s-1ROLLBACK\s0>. .SS "Transaction and Database Locking" .IX Subsection "Transaction and Database Locking" Transaction by \f(CW\*(C`AutoCommit\*(C'\fR or \f(CW\*(C`begin_work\*(C'\fR is nice and handy, but sometimes you may get an annoying \*(L"database is locked\*(R" error. This typically happens when someone begins a transaction, and tries to write to a database while other person is reading from the database (in another transaction). You might be surprised but SQLite doesn't lock a database when you just begin a normal (deferred) transaction to maximize concurrency. It reserves a lock when you issue a statement to write, but until you actually try to write with a \f(CW\*(C`commit\*(C'\fR statement, it allows other people to read from the database. However, reading from the database also requires \&\f(CW\*(C`shared lock\*(C'\fR, and that prevents to give you the \f(CW\*(C`exclusive lock\*(C'\fR you reserved, thus you get the \*(L"database is locked\*(R" error, and other people will get the same error if they try to write afterwards, as you still have a \f(CW\*(C`pending\*(C'\fR lock. \f(CW\*(C`busy_timeout\*(C'\fR doesn't help in this case. .PP To avoid this, set a transaction type explicitly. You can issue a \&\f(CW\*(C`begin immediate transaction\*(C'\fR (or \f(CW\*(C`begin exclusive transaction\*(C'\fR) for each transaction, or set \f(CW\*(C`sqlite_use_immediate_transaction\*(C'\fR database handle attribute to true (since 1.30_02) to always use an immediate transaction (even when you simply use \f(CW\*(C`begin_work\*(C'\fR or turn off the \f(CW\*(C`AutoCommit\*(C'\fR.). .PP .Vb 3 \& my $dbh = DBI\->connect("dbi:SQLite::memory:", "", "", { \& sqlite_use_immediate_transaction => 1, \& }); .Ve .PP Note that this works only when all of the connections use the same (non-deferred) transaction. See <http://sqlite.org/lockingv3.html> for locking details. .ie n .SS """$sth\->finish"" and Transaction Rollback" .el .SS "\f(CW$sth\->finish\fP and Transaction Rollback" .IX Subsection "$sth->finish and Transaction Rollback" As the \s-1DBI\s0 doc says, you almost certainly do \fBnot\fR need to call \*(L"finish\*(R" in \s-1DBI\s0 method if you fetch all rows (probably in a loop). However, there are several exceptions to this rule, and rolling-back of an unfinished \f(CW\*(C`SELECT\*(C'\fR statement is one of such exceptional cases. .PP SQLite prohibits \f(CW\*(C`ROLLBACK\*(C'\fR of unfinished \f(CW\*(C`SELECT\*(C'\fR statements in a transaction (See <http://sqlite.org/lang_transaction.html> for details). So you need to call \f(CW\*(C`finish\*(C'\fR before you issue a rollback. .PP .Vb 10 \& $sth = $dbh\->prepare("SELECT * FROM t"); \& $dbh\->begin_work; \& eval { \& $sth\->execute; \& $row = $sth\->fetch; \& ... \& die "For some reason"; \& ... \& }; \& if($@) { \& $sth\->finish; # You need this for SQLite \& $dbh\->rollback; \& } else { \& $dbh\->commit; \& } .Ve .SS "Processing Multiple Statements At A Time" .IX Subsection "Processing Multiple Statements At A Time" \&\s-1DBI\s0's statement handle is not supposed to process multiple statements at a time. So if you pass a string that contains multiple statements (a \f(CW\*(C`dump\*(C'\fR) to a statement handle (via \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`do\*(C'\fR), DBD::SQLite only processes the first statement, and discards the rest. .PP Since 1.30_01, you can retrieve those ignored (unprepared) statements via \f(CW\*(C`$sth\->{sqlite_unprepared_statements}\*(C'\fR. It usually contains nothing but white spaces, but if you really care, you can check this attribute to see if there's anything left undone. Also, if you set a \f(CW\*(C`sqlite_allow_multiple_statements\*(C'\fR attribute of a database handle to true when you connect to a database, \f(CW\*(C`do\*(C'\fR method automatically checks the \f(CW\*(C`sqlite_unprepared_statements\*(C'\fR attribute, and if it finds anything undone (even if what's left is just a single white space), it repeats the process again, to the end. .SS "Performance" .IX Subsection "Performance" SQLite is fast, very fast. Matt processed his 72MB log file with it, inserting the data (400,000+ rows) by using transactions and only committing every 1000 rows (otherwise the insertion is quite slow), and then performing queries on the data. .PP Queries like count(*) and avg(bytes) took fractions of a second to return, but what surprised him most of all was: .PP .Vb 5 \& SELECT url, count(*) as count \& FROM access_log \& GROUP BY url \& ORDER BY count desc \& LIMIT 20 .Ve .PP To discover the top 20 hit URLs on the site (<http://axkit.org>), and it returned within 2 seconds. He was seriously considering switching his log analysis code to use this little speed demon! .PP Oh yeah, and that was with no indexes on the table, on a 400MHz \s-1PIII\s0. .PP For best performance be sure to tune your hdparm settings if you are using linux. Also you might want to set: .PP .Vb 1 \& PRAGMA synchronous = OFF .Ve .PP Which will prevent sqlite from doing fsync's when writing (which slows down non-transactional writes significantly) at the expense of some peace of mind. Also try playing with the cache_size pragma. .PP The memory usage of SQLite can also be tuned using the cache_size pragma. .PP .Vb 1 \& $dbh\->do("PRAGMA cache_size = 800000"); .Ve .PP The above will allocate 800M for \s-1DB\s0 cache; the default is 2M. Your sweet spot probably lies somewhere in between. .SH "DRIVER PRIVATE ATTRIBUTES" .IX Header "DRIVER PRIVATE ATTRIBUTES" .SS "Database Handle Attributes" .IX Subsection "Database Handle Attributes" .IP "sqlite_version" 4 .IX Item "sqlite_version" Returns the version of the SQLite library which \fBDBD::SQLite\fR is using, e.g., \*(L"2.8.0\*(R". Can only be read. .IP "sqlite_unicode" 4 .IX Item "sqlite_unicode" If set to a true value, \fBDBD::SQLite\fR will turn the \s-1UTF\-8\s0 flag on for all text strings coming out of the database (this feature is currently disabled for perl < 5.8.5). For more details on the \s-1UTF\-8\s0 flag see perlunicode. The default is for the \s-1UTF\-8\s0 flag to be turned off. .Sp Also note that due to some bizarreness in SQLite's type system (see <http://www.sqlite.org/datatype3.html>), if you want to retain blob-style behavior for \fBsome\fR columns under \f(CW\*(C`$dbh\->{sqlite_unicode} = 1\*(C'\fR (say, to store images in the database), you have to state so explicitly using the 3\-argument form of \*(L"bind_param\*(R" in \s-1DBI\s0 when doing updates: .Sp .Vb 3 \& use DBI qw(:sql_types); \& $dbh\->{sqlite_unicode} = 1; \& my $sth = $dbh\->prepare("INSERT INTO mytable (blobcolumn) VALUES (?)"); \& \& # Binary_data will be stored as is. \& $sth\->bind_param(1, $binary_data, SQL_BLOB); .Ve .Sp Defining the column type as \f(CW\*(C`BLOB\*(C'\fR in the \s-1DDL\s0 is \fBnot\fR sufficient. .Sp This attribute was originally named as \f(CW\*(C`unicode\*(C'\fR, and renamed to \&\f(CW\*(C`sqlite_unicode\*(C'\fR for integrity since version 1.26_06. Old \f(CW\*(C`unicode\*(C'\fR attribute is still accessible but will be deprecated in the near future. .IP "sqlite_allow_multiple_statements" 4 .IX Item "sqlite_allow_multiple_statements" If you set this to true, \f(CW\*(C`do\*(C'\fR method will process multiple statements at one go. This may be handy, but with performance penalty. See above for details. .IP "sqlite_use_immediate_transaction" 4 .IX Item "sqlite_use_immediate_transaction" If you set this to true, DBD::SQLite tries to issue a \f(CW\*(C`begin immediate transaction\*(C'\fR (instead of \f(CW\*(C`begin transaction\*(C'\fR) when necessary. See above for details. .IP "sqlite_see_if_its_a_number" 4 .IX Item "sqlite_see_if_its_a_number" If you set this to true, DBD::SQLite tries to see if the bind values are number or not, and does not quote if they are numbers. See above for details. .SS "Statement Handle Attributes" .IX Subsection "Statement Handle Attributes" .IP "sqlite_unprepared_statements" 4 .IX Item "sqlite_unprepared_statements" Returns an unprepared part of the statement you pass to \f(CW\*(C`prepare\*(C'\fR. Typically this contains nothing but white spaces after a semicolon. See above for details. .SH "METHODS" .IX Header "METHODS" See also to the \s-1DBI\s0 documentation for the details of other common methods. .SS "table_info" .IX Subsection "table_info" .Vb 1 \& $sth = $dbh\->table_info(undef, $schema, $table, $type, \e%attr); .Ve .PP Returns all tables and schemas (databases) as specified in \*(L"table_info\*(R" in \s-1DBI\s0. The schema and table arguments will do a \f(CW\*(C`LIKE\*(C'\fR search. You can specify an \&\s-1ESCAPE\s0 character by including an 'Escape' attribute in \e%attr. The \f(CW$type\fR argument accepts a comma separated list of the following types '\s-1TABLE\s0', \&'\s-1VIEW\s0', '\s-1LOCAL\s0 \s-1TEMPORARY\s0' and '\s-1SYSTEM\s0 \s-1TABLE\s0' (by default all are returned). Note that a statement handle is returned, and not a direct list of tables. .PP The following fields are returned: .PP \&\fB\s-1TABLE_CAT\s0\fR: Always \s-1NULL\s0, as SQLite does not have the concept of catalogs. .PP \&\fB\s-1TABLE_SCHEM\s0\fR: The name of the schema (database) that the table or view is in. The default schema is 'main', temporary tables are in 'temp' and other databases will be in the name given when the database was attached. .PP \&\fB\s-1TABLE_NAME\s0\fR: The name of the table or view. .PP \&\fB\s-1TABLE_TYPE\s0\fR: The type of object returned. Will be one of '\s-1TABLE\s0', '\s-1VIEW\s0', \&'\s-1LOCAL\s0 \s-1TEMPORARY\s0' or '\s-1SYSTEM\s0 \s-1TABLE\s0'. .SS "primary_key, primary_key_info" .IX Subsection "primary_key, primary_key_info" .Vb 2 \& @names = $dbh\->primary_key(undef, $schema, $table); \& $sth = $dbh\->primary_key_info(undef, $schema, $table, \e%attr); .Ve .PP You can retrieve primary key names or more detailed information. As noted above, SQLite does not have the concept of catalogs, so the first argument of the mothods is usually \f(CW\*(C`undef\*(C'\fR, and you'll usually set \f(CW\*(C`undef\*(C'\fR for the second one (unless you want to know the primary keys of temporary tables). .SH "DRIVER PRIVATE METHODS" .IX Header "DRIVER PRIVATE METHODS" The following methods can be called via the \fIfunc()\fR method with a little tweak, but the use of \fIfunc()\fR method is now discouraged by the \s-1DBI\s0 author for various reasons (see \s-1DBI\s0's document http://search.cpan.org/dist/DBI/lib/DBI/DBD.pm#\fIUsing_install_method()\fR_to_expose_driver\-private_methods <http://search.cpan.org/dist/DBI/lib/DBI/DBD.pm#Using_install_method()_to_expose_driver-private_methods> for details). So, if you're using \s-1DBI\s0 >= 1.608, use these \f(CW\*(C`sqlite_\*(C'\fR methods. If you need to use an older \s-1DBI\s0, you can call these like this: .PP .Vb 1 \& $dbh\->func( ..., "(method name without sqlite_ prefix)" ); .Ve .PP Exception: \f(CW\*(C`sqlite_trace\*(C'\fR should always be called as is, even with \f(CW\*(C`func()\*(C'\fR method (to avoid conflict with \s-1DBI\s0's \fItrace()\fR method). .PP .Vb 1 \& $dbh\->func( ..., "sqlite_trace"); .Ve .ie n .SS "$dbh\->\fIsqlite_last_insert_rowid()\fP" .el .SS "\f(CW$dbh\fP\->\fIsqlite_last_insert_rowid()\fP" .IX Subsection "$dbh->sqlite_last_insert_rowid()" This method returns the last inserted rowid. If you specify an \s-1INTEGER\s0 \s-1PRIMARY\s0 \&\s-1KEY\s0 as the first column in your table, that is the column that is returned. Otherwise, it is the hidden \s-1ROWID\s0 column. See the sqlite docs for details. .PP Generally you should not be using this method. Use the \s-1DBI\s0 last_insert_id method instead. The usage of this is: .PP .Vb 1 \& $h\->last_insert_id($catalog, $schema, $table_name, $field_name [, \e%attr ]) .Ve .PP Running \f(CW\*(C`$h\->last_insert_id("","","","")\*(C'\fR is the equivalent of running \&\f(CW\*(C`$dbh\->sqlite_last_insert_rowid()\*(C'\fR directly. .ie n .SS "$dbh\->\fIsqlite_busy_timeout()\fP" .el .SS "\f(CW$dbh\fP\->\fIsqlite_busy_timeout()\fP" .IX Subsection "$dbh->sqlite_busy_timeout()" Retrieve the current busy timeout. .ie n .SS "$dbh\->sqlite_busy_timeout( $ms )" .el .SS "\f(CW$dbh\fP\->sqlite_busy_timeout( \f(CW$ms\fP )" .IX Subsection "$dbh->sqlite_busy_timeout( $ms )" Set the current busy timeout. The timeout is in milliseconds. .ie n .SS "$dbh\->sqlite_create_function( $name, $argc, $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_create_function( \f(CW$name\fP, \f(CW$argc\fP, \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_create_function( $name, $argc, $code_ref )" This method will register a new function which will be usable in an \s-1SQL\s0 query. The method's parameters are: .ie n .IP "$name" 4 .el .IP "\f(CW$name\fR" 4 .IX Item "$name" The name of the function. This is the name of the function as it will be used from \s-1SQL\s0. .ie n .IP "$argc" 4 .el .IP "\f(CW$argc\fR" 4 .IX Item "$argc" The number of arguments taken by the function. If this number is \-1, the function can take any number of arguments. .ie n .IP "$code_ref" 4 .el .IP "\f(CW$code_ref\fR" 4 .IX Item "$code_ref" This should be a reference to the function's implementation. .PP For example, here is how to define a \fInow()\fR function which returns the current number of seconds since the epoch: .PP .Vb 1 \& $dbh\->sqlite_create_function( \*(Aqnow\*(Aq, 0, sub { return time } ); .Ve .PP After this, it could be use from \s-1SQL\s0 as: .PP .Vb 1 \& INSERT INTO mytable ( now() ); .Ve .PP \fI\s-1REGEXP\s0 function\fR .IX Subsection "REGEXP function" .PP SQLite includes syntactic support for an infix operator '\s-1REGEXP\s0', but without any implementation. The \f(CW\*(C`DBD::SQLite\*(C'\fR driver automatically registers an implementation that performs standard perl regular expression matching, using current locale. So for example you can search for words starting with an 'A' with a query like .PP .Vb 1 \& SELECT * from table WHERE column REGEXP \*(Aq\ebA\ew+\*(Aq .Ve .PP If you want case-insensitive searching, use perl regex flags, like this : .PP .Vb 1 \& SELECT * from table WHERE column REGEXP \*(Aq(?i:\ebA\ew+)\*(Aq .Ve .PP The default \s-1REGEXP\s0 implementation can be overridden through the \&\f(CW\*(C`create_function\*(C'\fR \s-1API\s0 described above. .PP Note that regexp matching will \fBnot\fR use SQLite indices, but will iterate over all rows, so it could be quite costly in terms of performance. .ie n .SS "$dbh\->sqlite_create_collation( $name, $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_create_collation( \f(CW$name\fP, \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_create_collation( $name, $code_ref )" This method manually registers a new function which will be usable in an \s-1SQL\s0 query as a \s-1COLLATE\s0 option for sorting. Such functions can also be registered automatically on demand: see section \*(L"\s-1COLLATION\s0 \s-1FUNCTIONS\s0\*(R" below. .PP The method's parameters are: .ie n .IP "$name" 4 .el .IP "\f(CW$name\fR" 4 .IX Item "$name" The name of the function exposed to \s-1SQL\s0. .ie n .IP "$code_ref" 4 .el .IP "\f(CW$code_ref\fR" 4 .IX Item "$code_ref" Reference to the function's implementation. The driver will check that this is a proper sorting function. .ie n .SS "$dbh\->sqlite_collation_needed( $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_collation_needed( \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_collation_needed( $code_ref )" This method manually registers a callback function that will be invoked whenever an undefined collation sequence is required from an \s-1SQL\s0 statement. The callback is invoked as .PP .Vb 1 \& $code_ref\->($dbh, $collation_name) .Ve .PP and should register the desired collation using \&\*(L"sqlite_create_collation\*(R". .PP An initial callback is already registered by \f(CW\*(C`DBD::SQLite\*(C'\fR, so for most common cases it will be simpler to just add your collation sequences in the \f(CW%DBD::SQLite::COLLATION\fR hash (see section \*(L"\s-1COLLATION\s0 \s-1FUNCTIONS\s0\*(R" below). .ie n .SS "$dbh\->sqlite_create_aggregate( $name, $argc, $pkg )" .el .SS "\f(CW$dbh\fP\->sqlite_create_aggregate( \f(CW$name\fP, \f(CW$argc\fP, \f(CW$pkg\fP )" .IX Subsection "$dbh->sqlite_create_aggregate( $name, $argc, $pkg )" This method will register a new aggregate function which can then be used from \s-1SQL\s0. The method's parameters are: .ie n .IP "$name" 4 .el .IP "\f(CW$name\fR" 4 .IX Item "$name" The name of the aggregate function, this is the name under which the function will be available from \s-1SQL\s0. .ie n .IP "$argc" 4 .el .IP "\f(CW$argc\fR" 4 .IX Item "$argc" This is an integer which tells the \s-1SQL\s0 parser how many arguments the function takes. If that number is \-1, the function can take any number of arguments. .ie n .IP "$pkg" 4 .el .IP "\f(CW$pkg\fR" 4 .IX Item "$pkg" This is the package which implements the aggregator interface. .PP The aggregator interface consists of defining three methods: .IP "\fInew()\fR" 4 .IX Item "new()" This method will be called once to create an object which should be used to aggregate the rows in a particular group. The \fIstep()\fR and \&\fIfinalize()\fR methods will be called upon the reference return by the method. .IP "step(@_)" 4 .IX Item "step(@_)" This method will be called once for each row in the aggregate. .IP "\fIfinalize()\fR" 4 .IX Item "finalize()" This method will be called once all rows in the aggregate were processed and it should return the aggregate function's result. When there is no rows in the aggregate, \fIfinalize()\fR will be called right after \fInew()\fR. .PP Here is a simple aggregate function which returns the variance (example adapted from pysqlite): .PP .Vb 1 \& package variance; \& \& sub new { bless [], shift; } \& \& sub step { \& my ( $self, $value ) = @_; \& \& push @$self, $value; \& } \& \& sub finalize { \& my $self = $_[0]; \& \& my $n = @$self; \& \& # Variance is NULL unless there is more than one row \& return undef unless $n || $n == 1; \& \& my $mu = 0; \& foreach my $v ( @$self ) { \& $mu += $v; \& } \& $mu /= $n; \& \& my $sigma = 0; \& foreach my $v ( @$self ) { \& $sigma += ($x \- $mu)**2; \& } \& $sigma = $sigma / ($n \- 1); \& \& return $sigma; \& } \& \& $dbh\->sqlite_create_aggregate( "variance", 1, \*(Aqvariance\*(Aq ); .Ve .PP The aggregate function can then be used as: .PP .Vb 3 \& SELECT group_name, variance(score) \& FROM results \& GROUP BY group_name; .Ve .PP For more examples, see the DBD::SQLite::Cookbook. .ie n .SS "$dbh\->sqlite_progress_handler( $n_opcodes, $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_progress_handler( \f(CW$n_opcodes\fP, \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_progress_handler( $n_opcodes, $code_ref )" This method registers a handler to be invoked periodically during long running calls to SQLite. .PP An example use for this interface is to keep a \s-1GUI\s0 updated during a large query. The parameters are: .ie n .IP "$n_opcodes" 4 .el .IP "\f(CW$n_opcodes\fR" 4 .IX Item "$n_opcodes" The progress handler is invoked once for every \f(CW$n_opcodes\fR virtual machine opcodes in SQLite. .ie n .IP "$code_ref" 4 .el .IP "\f(CW$code_ref\fR" 4 .IX Item "$code_ref" Reference to the handler subroutine. If the progress handler returns non-zero, the SQLite operation is interrupted. This feature can be used to implement a \*(L"Cancel\*(R" button on a \s-1GUI\s0 dialog box. .Sp Set this argument to \f(CW\*(C`undef\*(C'\fR if you want to unregister a previous progress handler. .ie n .SS "$dbh\->sqlite_commit_hook( $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_commit_hook( \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_commit_hook( $code_ref )" This method registers a callback function to be invoked whenever a transaction is committed. Any callback set by a previous call to \&\f(CW\*(C`sqlite_commit_hook\*(C'\fR is overridden. A reference to the previous callback (if any) is returned. Registering an \f(CW\*(C`undef\*(C'\fR disables the callback. .PP When the commit hook callback returns zero, the commit operation is allowed to continue normally. If the callback returns non-zero, then the commit is converted into a rollback (in that case, any attempt to \&\fIexplicitly\fR call \f(CW\*(C`$dbh\->rollback()\*(C'\fR afterwards would yield an error). .ie n .SS "$dbh\->sqlite_rollback_hook( $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_rollback_hook( \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_rollback_hook( $code_ref )" This method registers a callback function to be invoked whenever a transaction is rolled back. Any callback set by a previous call to \&\f(CW\*(C`sqlite_rollback_hook\*(C'\fR is overridden. A reference to the previous callback (if any) is returned. Registering an \f(CW\*(C`undef\*(C'\fR disables the callback. .ie n .SS "$dbh\->sqlite_update_hook( $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_update_hook( \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_update_hook( $code_ref )" This method registers a callback function to be invoked whenever a row is updated, inserted or deleted. Any callback set by a previous call to \&\f(CW\*(C`sqlite_update_hook\*(C'\fR is overridden. A reference to the previous callback (if any) is returned. Registering an \f(CW\*(C`undef\*(C'\fR disables the callback. .PP The callback will be called as .PP .Vb 1 \& $code_ref\->($action_code, $database, $table, $rowid) .Ve .PP where .ie n .IP "$action_code" 4 .el .IP "\f(CW$action_code\fR" 4 .IX Item "$action_code" is an integer equal to either \f(CW\*(C`DBD::SQLite::INSERT\*(C'\fR, \&\f(CW\*(C`DBD::SQLite::DELETE\*(C'\fR or \f(CW\*(C`DBD::SQLite::UPDATE\*(C'\fR (see \*(L"Action Codes\*(R"); .ie n .IP "$database" 4 .el .IP "\f(CW$database\fR" 4 .IX Item "$database" is the name of the database containing the affected row; .ie n .IP "$table" 4 .el .IP "\f(CW$table\fR" 4 .IX Item "$table" is the name of the table containing the affected row; .ie n .IP "$rowid" 4 .el .IP "\f(CW$rowid\fR" 4 .IX Item "$rowid" is the unique 64\-bit signed integer key of the affected row within that table. .ie n .SS "$dbh\->sqlite_set_authorizer( $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_set_authorizer( \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_set_authorizer( $code_ref )" This method registers an authorizer callback to be invoked whenever \&\s-1SQL\s0 statements are being compiled by the \*(L"prepare\*(R" in \s-1DBI\s0 method. The authorizer callback should return \f(CW\*(C`DBD::SQLite::OK\*(C'\fR to allow the action, \f(CW\*(C`DBD::SQLite::IGNORE\*(C'\fR to disallow the specific action but allow the \s-1SQL\s0 statement to continue to be compiled, or \&\f(CW\*(C`DBD::SQLite::DENY\*(C'\fR to cause the entire \s-1SQL\s0 statement to be rejected with an error. If the authorizer callback returns any other value, then then \f(CW\*(C`prepare\*(C'\fR call that triggered the authorizer will fail with an error message. .PP An authorizer is used when preparing \s-1SQL\s0 statements from an untrusted source, to ensure that the \s-1SQL\s0 statements do not try to access data they are not allowed to see, or that they do not try to execute malicious statements that damage the database. For example, an application may allow a user to enter arbitrary \s-1SQL\s0 queries for evaluation by a database. But the application does not want the user to be able to make arbitrary changes to the database. An authorizer could then be put in place while the user-entered \s-1SQL\s0 is being prepared that disallows everything except \s-1SELECT\s0 statements. .PP The callback will be called as .PP .Vb 1 \& $code_ref\->($action_code, $string1, $string2, $database, $trigger_or_view) .Ve .PP where .ie n .IP "$action_code" 4 .el .IP "\f(CW$action_code\fR" 4 .IX Item "$action_code" is an integer that specifies what action is being authorized (see \*(L"Action Codes\*(R"). .ie n .IP "$string1, $string2" 4 .el .IP "\f(CW$string1\fR, \f(CW$string2\fR" 4 .IX Item "$string1, $string2" are strings that depend on the action code (see \*(L"Action Codes\*(R"). .ie n .IP "$database" 4 .el .IP "\f(CW$database\fR" 4 .IX Item "$database" is the name of the database (\f(CW\*(C`main\*(C'\fR, \f(CW\*(C`temp\*(C'\fR, etc.) if applicable. .ie n .IP "$trigger_or_view" 4 .el .IP "\f(CW$trigger_or_view\fR" 4 .IX Item "$trigger_or_view" is the name of the inner-most trigger or view that is responsible for the access attempt, or \f(CW\*(C`undef\*(C'\fR if this access attempt is directly from top-level \s-1SQL\s0 code. .ie n .SS "$dbh\->sqlite_backup_from_file( $filename )" .el .SS "\f(CW$dbh\fP\->sqlite_backup_from_file( \f(CW$filename\fP )" .IX Subsection "$dbh->sqlite_backup_from_file( $filename )" This method accesses the SQLite Online Backup \s-1API\s0, and will take a backup of the named database file, copying it to, and overwriting, your current database connection. This can be particularly handy if your current connection is to the special :memory: database, and you wish to populate it from an existing \s-1DB\s0. .ie n .SS "$dbh\->sqlite_backup_to_file( $filename )" .el .SS "\f(CW$dbh\fP\->sqlite_backup_to_file( \f(CW$filename\fP )" .IX Subsection "$dbh->sqlite_backup_to_file( $filename )" This method accesses the SQLite Online Backup \s-1API\s0, and will take a backup of the currently connected database, and write it out to the named file. .ie n .SS "$dbh\->sqlite_enable_load_extension( $bool )" .el .SS "\f(CW$dbh\fP\->sqlite_enable_load_extension( \f(CW$bool\fP )" .IX Subsection "$dbh->sqlite_enable_load_extension( $bool )" Calling this method with a true value enables loading (external) sqlite3 extensions. After the call, you can load extensions like this: .PP .Vb 3 \& $dbh\->sqlite_enable_load_extension(1); \& $sth = $dbh\->prepare("select load_extension(\*(Aqlibsqlitefunctions.so\*(Aq)") \& or die "Cannot prepare: " . $dbh\->errstr(); .Ve .ie n .SS "$dbh\->sqlite_trace( $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_trace( \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_trace( $code_ref )" This method registers a trace callback to be invoked whenever \&\s-1SQL\s0 statements are being run. .PP The callback will be called as .PP .Vb 1 \& $code_ref\->($statement) .Ve .PP where .ie n .IP "$statement" 4 .el .IP "\f(CW$statement\fR" 4 .IX Item "$statement" is a \s-1UTF\-8\s0 rendering of the \s-1SQL\s0 statement text as the statement first begins executing. .PP Additional callbacks might occur as each triggered subprogram is entered. The callbacks for triggers contain a \s-1UTF\-8\s0 \s-1SQL\s0 comment that identifies the trigger. .PP See also \*(L"\s-1TRACING\s0\*(R" in \s-1DBI\s0 for better tracing options. .ie n .SS "$dbh\->sqlite_profile( $code_ref )" .el .SS "\f(CW$dbh\fP\->sqlite_profile( \f(CW$code_ref\fP )" .IX Subsection "$dbh->sqlite_profile( $code_ref )" This method registers a profile callback to be invoked whenever a \s-1SQL\s0 statement finishes. .PP The callback will be called as .PP .Vb 1 \& $code_ref\->($statement, $elapsed_time) .Ve .PP where .ie n .IP "$statement" 4 .el .IP "\f(CW$statement\fR" 4 .IX Item "$statement" is the original statement text (without bind parameters). .ie n .IP "$elapsed_time" 4 .el .IP "\f(CW$elapsed_time\fR" 4 .IX Item "$elapsed_time" is an estimate of wall-clock time of how long that statement took to run (in milliseconds). .PP This method is considered experimental and is subject to change in future versions of SQLite. .PP See also DBI::Profile for better profiling options. .SS "\fIDBD::SQLite::compile_options()\fP" .IX Subsection "DBD::SQLite::compile_options()" Returns an array of compile options (available since sqlite 3.6.23, bundled in DBD::SQLite 1.30_01), or an empty array if the bundled library is old or compiled with \s-1SQLITE_OMIT_COMPILEOPTION_DIAGS\s0. .SH "DRIVER CONSTANTS" .IX Header "DRIVER CONSTANTS" A subset of SQLite C constants are made available to Perl, because they may be needed when writing hooks or authorizer callbacks. For accessing such constants, the \f(CW\*(C`DBD::SQLite\*(C'\fR module must be explicitly \f(CW\*(C`use\*(C'\fRd at compile time. For example, an authorizer that forbids any \&\s-1DELETE\s0 operation would be written as follows : .PP .Vb 6 \& use DBD::SQLite; \& $dbh\->sqlite_set_authorizer(sub { \& my $action_code = shift; \& return $action_code == DBD::SQLite::DELETE ? DBD::SQLite::DENY \& : DBD::SQLite::OK; \& }); .Ve .PP The list of constants implemented in \f(CW\*(C`DBD::SQLite\*(C'\fR is given below; more information can be found ad at <http://www.sqlite.org/c3ref/constlist.html>. .SS "Authorizer Return Codes" .IX Subsection "Authorizer Return Codes" .Vb 3 \& OK \& DENY \& IGNORE .Ve .SS "Action Codes" .IX Subsection "Action Codes" The \*(L"set_authorizer\*(R" method registers a callback function that is invoked to authorize certain \s-1SQL\s0 statement actions. The first parameter to the callback is an integer code that specifies what action is being authorized. The second and third parameters to the callback are strings, the meaning of which varies according to the action code. Below is the list of action codes, together with their associated strings. .PP .Vb 10 \& # constant string1 string2 \& # ======== ======= ======= \& CREATE_INDEX Index Name Table Name \& CREATE_TABLE Table Name undef \& CREATE_TEMP_INDEX Index Name Table Name \& CREATE_TEMP_TABLE Table Name undef \& CREATE_TEMP_TRIGGER Trigger Name Table Name \& CREATE_TEMP_VIEW View Name undef \& CREATE_TRIGGER Trigger Name Table Name \& CREATE_VIEW View Name undef \& DELETE Table Name undef \& DROP_INDEX Index Name Table Name \& DROP_TABLE Table Name undef \& DROP_TEMP_INDEX Index Name Table Name \& DROP_TEMP_TABLE Table Name undef \& DROP_TEMP_TRIGGER Trigger Name Table Name \& DROP_TEMP_VIEW View Name undef \& DROP_TRIGGER Trigger Name Table Name \& DROP_VIEW View Name undef \& INSERT Table Name undef \& PRAGMA Pragma Name 1st arg or undef \& READ Table Name Column Name \& SELECT undef undef \& TRANSACTION Operation undef \& UPDATE Table Name Column Name \& ATTACH Filename undef \& DETACH Database Name undef \& ALTER_TABLE Database Name Table Name \& REINDEX Index Name undef \& ANALYZE Table Name undef \& CREATE_VTABLE Table Name Module Name \& DROP_VTABLE Table Name Module Name \& FUNCTION undef Function Name \& SAVEPOINT Operation Savepoint Name .Ve .SH "COLLATION FUNCTIONS" .IX Header "COLLATION FUNCTIONS" .SS "Definition" .IX Subsection "Definition" SQLite v3 provides the ability for users to supply arbitrary comparison functions, known as user-defined \*(L"collation sequences\*(R" or \&\*(L"collating functions\*(R", to be used for comparing two text values. <http://www.sqlite.org/datatype3.html#collation> explains how collations are used in various \s-1SQL\s0 expressions. .SS "Builtin collation sequences" .IX Subsection "Builtin collation sequences" The following collation sequences are builtin within SQLite : .IP "\fB\s-1BINARY\s0\fR" 4 .IX Item "BINARY" Compares string data using \fImemcmp()\fR, regardless of text encoding. .IP "\fB\s-1NOCASE\s0\fR" 4 .IX Item "NOCASE" The same as binary, except the 26 upper case characters of \s-1ASCII\s0 are folded to their lower case equivalents before the comparison is performed. Note that only \s-1ASCII\s0 characters are case folded. SQLite does not attempt to do full \s-1UTF\s0 case folding due to the size of the tables required. .IP "\fB\s-1RTRIM\s0\fR" 4 .IX Item "RTRIM" The same as binary, except that trailing space characters are ignored. .PP In addition, \f(CW\*(C`DBD::SQLite\*(C'\fR automatically installs the following collation sequences : .IP "\fBperl\fR" 4 .IX Item "perl" corresponds to the Perl \f(CW\*(C`cmp\*(C'\fR operator .IP "\fBperllocale\fR" 4 .IX Item "perllocale" Perl \f(CW\*(C`cmp\*(C'\fR operator, in a context where \f(CW\*(C`use locale\*(C'\fR is activated. .SS "Usage" .IX Subsection "Usage" You can write for example .PP .Vb 5 \& CREATE TABLE foo( \& txt1 COLLATE perl, \& txt2 COLLATE perllocale, \& txt3 COLLATE nocase \& ) .Ve .PP or .PP .Vb 1 \& SELECT * FROM foo ORDER BY name COLLATE perllocale .Ve .SS "Unicode handling" .IX Subsection "Unicode handling" If the attribute \f(CW\*(C`$dbh\->{sqlite_unicode}\*(C'\fR is set, strings coming from the database and passed to the collation function will be properly tagged with the utf8 flag; but this only works if the \&\f(CW\*(C`sqlite_unicode\*(C'\fR attribute is set \fBbefore\fR the first call to a perl collation sequence . The recommended way to activate unicode is to set the parameter at connection time : .PP .Vb 7 \& my $dbh = DBI\->connect( \& "dbi:SQLite:dbname=foo", "", "", \& { \& RaiseError => 1, \& sqlite_unicode => 1, \& } \& ); .Ve .SS "Adding user-defined collations" .IX Subsection "Adding user-defined collations" The native SQLite \s-1API\s0 for adding user-defined collations is exposed through methods \*(L"sqlite_create_collation\*(R" and \&\*(L"sqlite_collation_needed\*(R". .PP To avoid calling these functions every time a \f(CW$dbh\fR handle is created, \f(CW\*(C`DBD::SQLite\*(C'\fR offers a simpler interface through the \&\f(CW%DBD::SQLite::COLLATION\fR hash : just insert your own collation functions in that hash, and whenever an unknown collation name is encountered in \s-1SQL\s0, the appropriate collation function will be loaded on demand from the hash. For example, here is a way to sort text values regardless of their accented characters : .PP .Vb 10 \& use DBD::SQLite; \& $DBD::SQLite::COLLATION{no_accents} = sub { \& my ( $a, $b ) = map lc, @_; \& tr[XXXXXXXXXXXXXXXXXXXXXXXXXXXX] \& [aaaaaacdeeeeiiiinoooooouuuuy] for $a, $b; \& $a cmp $b; \& }; \& my $dbh = DBI\->connect("dbi:SQLite:dbname=dbfile"); \& my $sql = "SELECT ... FROM ... ORDER BY ... COLLATE no_accents"); \& my $rows = $dbh\->selectall_arrayref($sql); .Ve .PP The builtin \f(CW\*(C`perl\*(C'\fR or \f(CW\*(C`perllocale\*(C'\fR collations are predefined in that same hash. .PP The \s-1COLLATION\s0 hash is a global registry within the current process; hence there is a risk of undesired side-effects. Therefore, to prevent action at distance, the hash is implemented as a \*(L"write-only\*(R" hash, that will happily accept new entries, but will raise an exception if any attempt is made to override or delete a existing entry (including the builtin \f(CW\*(C`perl\*(C'\fR and \f(CW\*(C`perllocale\*(C'\fR). .PP If you really, really need to change or delete an entry, you can always grab the tied object underneath \f(CW%DBD::SQLite::COLLATION\fR \-\-\- but don't do that unless you really know what you are doing. Also observe that changes in the global hash will not modify existing collations in existing database handles: it will only affect new \&\fIrequests\fR for collations. In other words, if you want to change the behaviour of a collation within an existing \f(CW$dbh\fR, you need to call the \*(L"create_collation\*(R" method directly. .SH "FULLTEXT SEARCH" .IX Header "FULLTEXT SEARCH" The \s-1FTS3\s0 extension module within SQLite allows users to create special tables with a built-in full-text index (hereafter \*(L"\s-1FTS3\s0 tables\*(R"). The full-text index allows the user to efficiently query the database for all rows that contain one or more instances of a specified word (hereafter a \*(L"token\*(R"), even if the table contains many large documents. .SS "Short introduction to \s-1FTS3\s0" .IX Subsection "Short introduction to FTS3" The detailed documentation for \s-1FTS3\s0 can be found at <http://www.sqlite.org/fts3.html>. Here is a very short example : .PP .Vb 2 \& $dbh\->do(<<"") or die DBI::errstr; \& CREATE VIRTUAL TABLE fts_example USING fts3(content) \& \& my $sth = $dbh\->prepare("INSERT INTO fts_example(content) VALUES (?))"); \& $sth\->execute($_) foreach @docs_to_insert; \& \& my $results = $dbh\->selectall_arrayref(<<""); \& SELECT docid, snippet(content) FROM fts_example WHERE content MATCH \*(Aqfoo\*(Aq .Ve .PP The key points in this example are : .IP "\(bu" 4 The syntax for creating \s-1FTS3\s0 tables is .Sp .Vb 1 \& CREATE VIRTUAL TABLE <table_name> USING fts3(<columns>) .Ve .Sp where \f(CW\*(C`<columns>\*(C'\fR is a list of column names. Columns may be typed, but the type information is ignored. If no columns are specified, the default is a single column named \f(CW\*(C`content\*(C'\fR. In addition, \s-1FTS3\s0 tables have an implicit column called \f(CW\*(C`docid\*(C'\fR (or also \f(CW\*(C`rowid\*(C'\fR) for numbering the stored documents. .IP "\(bu" 4 Statements for inserting, updating or deleting records use the same syntax as for regular SQLite tables. .IP "\(bu" 4 Full-text searches are specified with the \f(CW\*(C`MATCH\*(C'\fR operator, and an operand which may be a single word, a word prefix ending with '*', a list of words, a \*(L"phrase query\*(R" in double quotes, or a boolean combination of the above. .IP "\(bu" 4 The builtin function \f(CW\*(C`snippet(...)\*(C'\fR builds a formatted excerpt of the document text, where the words pertaining to the query are highlighted. .PP There are many more details to building and searching \&\s-1FTS3\s0 tables, so we strongly invite you to read the full documentation at at <http://www.sqlite.org/fts3.html>. .PP \&\fBIncompatible change\fR : starting from version 1.31, \f(CW\*(C`DBD::SQLite\*(C'\fR uses the new, recommended \&\*(L"Enhanced Query Syntax\*(R" for binary set operators (\s-1AND\s0, \s-1OR\s0, \s-1NOT\s0, possibly nested with parenthesis). Previous versions of \f(CW\*(C`DBD::SQLite\*(C'\fR used the \&\*(L"Standard Query Syntax\*(R" (see <http://www.sqlite.org/fts3.html#section_3_2>). Unfortunately this is a compilation switch, so it cannot be tuned at runtime; however, since \s-1FTS3\s0 was never advertised in versions prior to 1.31, the change should be invisible to the vast majority of \&\f(CW\*(C`DBD::SQLite\*(C'\fR users. If, however, there are any applications that nevertheless were built using the \*(L"Standard Query\*(R" syntax, they have to be migrated, because the precedence of the \f(CW\*(C`OR\*(C'\fR operator has changed. Conversion from old to new syntax can be automated through DBD::SQLite::FTS3Transitional, published in a separate distribution. .SS "Tokenizers" .IX Subsection "Tokenizers" The behaviour of full-text indexes strongly depends on how documents are split into \fItokens\fR; therefore \s-1FTS3\s0 table declarations can explicitly specify how to perform tokenization: .PP .Vb 1 \& CREATE ... USING fts3(<columns>, tokenize=<tokenizer>) .Ve .PP where \f(CW\*(C`<tokenizer>\*(C'\fR is a sequence of space-separated words that triggers a specific tokenizer, as explained below. .PP \fISQLite builtin tokenizers\fR .IX Subsection "SQLite builtin tokenizers" .PP SQLite comes with three builtin tokenizers : .IP "simple" 4 .IX Item "simple" Under the \fIsimple\fR tokenizer, a term is a contiguous sequence of eligible characters, where eligible characters are all alphanumeric characters, the \*(L"_\*(R" character, and all characters with \s-1UTF\s0 codepoints greater than or equal to 128. All other characters are discarded when splitting a document into terms. They serve only to separate adjacent terms. .Sp All uppercase characters within the \s-1ASCII\s0 range (\s-1UTF\s0 codepoints less than 128), are transformed to their lowercase equivalents as part of the tokenization process. Thus, full-text queries are case-insensitive when using the simple tokenizer. .IP "porter" 4 .IX Item "porter" The \fIporter\fR tokenizer uses the same rules to separate the input document into terms, but as well as folding all terms to lower case it uses the Porter Stemming algorithm to reduce related English language words to a common root. .IP "icu" 4 .IX Item "icu" If SQLite is compiled with the \s-1SQLITE_ENABLE_ICU\s0 pre-processor symbol defined, then there exists a built-in tokenizer named \*(L"icu\*(R" implemented using the \s-1ICU\s0 library, and taking an \&\s-1ICU\s0 locale identifier as argument (such as \*(L"tr_TR\*(R" for Turkish as used in Turkey, or \*(L"en_AU\*(R" for English as used in Australia). For example: .Sp .Vb 1 \& CREATE VIRTUAL TABLE thai_text USING fts3(text, tokenize=icu th_TH) .Ve .Sp The \s-1ICU\s0 tokenizer implementation is very simple. It splits the input text according to the \s-1ICU\s0 rules for finding word boundaries and discards any tokens that consist entirely of white-space. This may be suitable for some applications in some locales, but not all. If more complex processing is required, for example to implement stemming or discard punctuation, use the perl tokenizer as explained below. .PP \fIPerl tokenizers\fR .IX Subsection "Perl tokenizers" .PP In addition to the builtin SQLite tokenizers, \f(CW\*(C`DBD::SQLite\*(C'\fR implements a \fIperl\fR tokenizer, that can hook to any tokenizing algorithm written in Perl. This is specified as follows : .PP .Vb 1 \& CREATE ... USING fts3(<columns>, tokenize=perl \*(Aq<perl_function>\*(Aq) .Ve .PP where \f(CW\*(C`<perl_function>\*(C'\fR is a fully qualified Perl function name (i.e. prefixed by the name of the package in which that function is declared). So for example if the function is \f(CW\*(C`my_func\*(C'\fR in the main program, write .PP .Vb 1 \& CREATE ... USING fts3(<columns>, tokenize=perl \*(Aqmain::my_func\*(Aq) .Ve .PP That function should return a code reference that takes a string as single argument, and returns an iterator (another function), which returns a tuple \f(CW\*(C`($term, $len, $start, $end, $index)\*(C'\fR for each term. Here is a simple example that tokenizes on words according to the current perl locale .PP .Vb 3 \& sub locale_tokenizer { \& return sub { \& my $string = shift; \& \& use locale; \& my $regex = qr/\ew+/; \& my $term_index = 0; \& \& return sub { # closure \& $string =~ /$regex/g or return; # either match, or no more token \& my ($start, $end) = ($\-[0], $+[0]); \& my $len = $end\-$start; \& my $term = substr($string, $start, $len); \& return ($term, $len, $start, $end, $term_index++); \& } \& }; \& } .Ve .PP There must be three levels of subs, in a kind of \*(L"Russian dolls\*(R" structure, because : .IP "\(bu" 4 the external, named sub is called whenever accessing a \s-1FTS3\s0 table with that tokenizer .IP "\(bu" 4 the inner, anonymous sub is called whenever a new string needs to be tokenized (either for inserting new text into the table, or for analyzing a query). .IP "\(bu" 4 the innermost, anonymous sub is called repeatedly for retrieving all terms within that string. .PP Instead of writing tokenizers by hand, you can grab one of those already implemented in the Search::Tokenizer module : .PP .Vb 4 \& use Search::Tokenizer; \& $dbh\->do(<<"") or die DBI::errstr; \& CREATE ... USING fts3(<columns>, \& tokenize=perl \*(AqSearch::Tokenizer::unaccent\*(Aq) .Ve .PP or you can use \*(L"new\*(R" in Search::Tokenizer to build your own tokenizer. .SS "Incomplete handling of utf8 characters" .IX Subsection "Incomplete handling of utf8 characters" The current \s-1FTS3\s0 implementation in SQLite is far from complete with respect to utf8 handling : in particular, variable-length characters are not treated correctly by the builtin functions \&\f(CW\*(C`offsets()\*(C'\fR and \f(CW\*(C`snippet()\*(C'\fR. .SS "Database space for \s-1FTS3\s0" .IX Subsection "Database space for FTS3" \&\s-1FTS3\s0 stores a complete copy of the indexed documents, together with the fulltext index. On a large collection of documents, this can consume quite a lot of disk space. If copies of documents are also available as external resources (for example files on the filesystem), that space can sometimes be spared \-\-\- see the tip in the Cookbook. .SH "R* TREE SUPPORT" .IX Header "R* TREE SUPPORT" The \s-1RTREE\s0 extension module within SQLite adds support for creating a R\-Tree, a special index for range and multidimensional queries. This allows users to create tables that can be loaded with (as an example) geospatial data such as latitude/longitude coordinates for buildings within a city : .PP .Vb 5 \& CREATE VIRTUAL TABLE city_buildings USING rtree( \& id, \-\- Integer primary key \& minLong, maxLong, \-\- Minimum and maximum longitude \& minLat, maxLat \-\- Minimum and maximum latitude \& ); .Ve .PP then query which buildings overlap or are contained within a specified region: .PP .Vb 5 \& # IDs that are contained within query coordinates \& my $contained_sql = <<""; \& SELECT id FROM try_rtree \& WHERE minLong >= ? AND maxLong <= ? \& AND minLat >= ? AND maxLat <= ? \& \& # ... and those that overlap query coordinates \& my $overlap_sql = <<""; \& SELECT id FROM try_rtree \& WHERE maxLong >= ? AND minLong <= ? \& AND maxLat >= ? AND minLat <= ? \& \& my $contained = $dbh\->selectcol_arrayref($contained_sql,undef, \& $minLong, $maxLong, $minLat, $maxLat); \& \& my $overlapping = $dbh\->selectcol_arrayref($overlap_sql,undef, \& $minLong, $maxLong, $minLat, $maxLat); .Ve .PP For more detail, please see the SQLite R\-Tree page (<http://www.sqlite.org/rtree.html>). Note that custom R\-Tree queries using callbacks, as mentioned in the prior link, have not been implemented yet. .SH "FOR DBD::SQLITE EXTENSION AUTHORS" .IX Header "FOR DBD::SQLITE EXTENSION AUTHORS" Since 1.30_01, you can retrieve the bundled sqlite C source and/or header like this: .PP .Vb 2 \& use File::ShareDir \*(Aqdist_dir\*(Aq; \& use File::Spec::Functions \*(Aqcatfile\*(Aq; \& \& # the whole sqlite3.h header \& my $sqlite3_h = catfile(dist_dir(\*(AqDBD\-SQLite\*(Aq), \*(Aqsqlite3.h\*(Aq); \& \& # or only a particular header, amalgamated in sqlite3.c \& my $what_i_want = \*(Aqparse.h\*(Aq; \& my $sqlite3_c = catfile(dist_dir(\*(AqDBD\-SQLite\*(Aq), \*(Aqsqlite3.c\*(Aq); \& open my $fh, \*(Aq<\*(Aq, $sqlite3_c or die $!; \& my $code = do { local $/; <$fh> }; \& my ($parse_h) = $code =~ m{( \& /\e*+[ ]Begin[ ]file[ ]$what_i_want[ ]\e*+ \& .+? \& /\e*+[ ]End[ ]of[ ]$what_i_want[ ]\e*+/ \& )}sx; \& open my $out, \*(Aq>\*(Aq, $what_i_want or die $!; \& print $out $parse_h; \& close $out; .Ve .PP You usually want to use this in your extension's \f(CW\*(C`Makefile.PL\*(C'\fR, and you may want to add DBD::SQLite to your extension's \f(CW\*(C`CONFIGURE_REQUIRES\*(C'\fR to ensure your extension users use the same C source/header they use to build DBD::SQLite itself (instead of the ones installed in their system). .SH "TO DO" .IX Header "TO DO" The following items remain to be done. .SS "Leak Detection" .IX Subsection "Leak Detection" Implement one or more leak detection tests that only run during \&\s-1AUTOMATED_TESTING\s0 and \s-1RELEASE_TESTING\s0 and validate that none of the C code we work with leaks. .SS "Stream \s-1API\s0 for Blobs" .IX Subsection "Stream API for Blobs" Reading/writing into blobs using \f(CW\*(C`sqlite2_blob_open\*(C'\fR / \f(CW\*(C`sqlite2_blob_close\*(C'\fR. .SS "Flags for sqlite3_open_v2" .IX Subsection "Flags for sqlite3_open_v2" Support the full \s-1API\s0 of sqlite3_open_v2 (flags for opening the file). .SS "Support for custom callbacks for R\-Tree queries" .IX Subsection "Support for custom callbacks for R-Tree queries" Custom queries of a R\-Tree index using a callback are possible with the SQLite C \s-1API\s0 (<http://www.sqlite.org/rtree.html>), so one could potentially use a callback that narrowed the result set down based on a specific need, such as querying for overlapping circles. .SH "SUPPORT" .IX Header "SUPPORT" Bugs should be reported via the \s-1CPAN\s0 bug tracker at .PP http://rt.cpan.org/NoAuth/ReportBug.html?Queue=DBD\-SQLite <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=DBD-SQLite> .PP Note that bugs of bundled sqlite library (i.e. bugs in \f(CW\*(C`sqlite3.[ch]\*(C'\fR) should be reported to the sqlite developers at sqlite.org via their bug tracker or via their mailing list. .SH "AUTHORS" .IX Header "AUTHORS" Matt Sergeant <matt@sergeant.org> .PP Francis J. Lacoste <flacoste@logreport.org> .PP Wolfgang Sourdeau <wolfgang@logreport.org> .PP Adam Kennedy <adamk@cpan.org> .PP Max Maischein <corion@cpan.org> .PP Laurent Dami <dami@cpan.org> .PP Kenichi Ishigaki <ishigaki@cpan.org> .SH "COPYRIGHT" .IX Header "COPYRIGHT" The bundled SQLite code in this distribution is Public Domain. .PP DBD::SQLite is copyright 2002 \- 2007 Matt Sergeant. .PP Some parts copyright 2008 Francis J. Lacoste. .PP Some parts copyright 2008 Wolfgang Sourdeau. .PP Some parts copyright 2008 \- 2012 Adam Kennedy. .PP Some parts copyright 2009 \- 2012 Kenichi Ishigaki. .PP Some parts derived from DBD::SQLite::Amalgamation copyright 2008 Audrey Tang. .PP This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. .PP The full text of the license can be found in the \&\s-1LICENSE\s0 file included with this module.