File: //usr/local/share/man/man3/DBD::SQLite.3
.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sh \" Subsection heading
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
.PP
..
.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. | will give a
.\" real vertical bar. \*(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-|\(bv\*(Tr
.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\}
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
.\" entries marked with X<> in POD. Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.if \nF \{\
. de IX
. tm Index:\\$1\t\\n%\t"\\$2"
..
. nr % 0
. rr F
.\}
.\"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.hy 0
.if n .na
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear. Run. Save yourself. 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 "2009-11-23" "perl v5.8.8" "User Contributed Perl Documentation"
.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"
.Sh "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.
.Sh "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.
.Sh "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","","");
.Ve
.PP
.Vb 4
\& 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];
.Ve
.PP
.Vb 1
\& # now $blobo == $blob
.Ve
.Sh "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 two 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't forget this
.Ve
.Sp
.Vb 5
\& 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
.Sh "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 with 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.
.Sh "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`foreign_keys\*(C'\fR above) for you when you connect to a database.
See <http://www.sqlite.org/pragma.html> for details.
.Sh "Performance"
.IX Subsection "Performance"
SQLite is fast, very fast. Matt processed my 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 default_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
\& $dbh->do("PRAGMA cache_size = 800000");
.Ve
.PP
The above will allocate 800M for \s-1DB\s0 cache; the default is 2M.
Your sweet spot probably lies somewhere in between.
.SH "DRIVER PRIVATE ATTRIBUTES"
.IX Header "DRIVER PRIVATE ATTRIBUTES"
.Sh "Database Handle Attributes"
.IX Subsection "Database Handle Attributes"
.IP "sqlite_version" 4
.IX Item "sqlite_version"
Returns the version of the SQLite library which \fBDBD::SQLite\fR is using,
e.g., \*(L"2.8.0\*(R". Can only be read.
.IP "sqlite_unicode" 4
.IX Item "sqlite_unicode"
If set to a true value, \fBDBD::SQLite\fR will turn the \s-1UTF\-8\s0 flag on for all
text strings coming out of the database (this feature is currently disabled
for perl < 5.8.5). For more details on the \s-1UTF\-8\s0 flag see
perlunicode. The default is for the \s-1UTF\-8\s0 flag to be turned off.
.Sp
Also note that due to some bizarreness in SQLite's type system (see
<http://www.sqlite.org/datatype3.html>), if you want to retain
blob-style behavior for \fBsome\fR columns under \f(CW\*(C`$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 (?)");
.Ve
.Sp
.Vb 2
\& # 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.
.SH "METHODS"
.IX Header "METHODS"
.Sh "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 seperated 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'.
.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>
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
\& $dbh->func( ..., "(method name without sqlite_ prefix)" );
.Ve
.Sh "$dbh\->\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`$dbh\->sqlite_last_insert_rowid()\*(C'\fR directly.
.Sh "$dbh\->\fIsqlite_busy_timeout()\fP"
.IX Subsection "$dbh->sqlite_busy_timeout()"
Retrieve the current busy timeout.
.ie n .Sh "$dbh\->sqlite_busy_timeout( $ms )"
.el .Sh "$dbh\->sqlite_busy_timeout( \f(CW$ms\fP )"
.IX Subsection "$dbh->sqlite_busy_timeout( $ms )"
Set the current busy timeout. The timeout is in milliseconds.
.ie n .Sh "$dbh\->sqlite_create_function( $name\fP, \f(CW$argc\fP, \f(CW$code_ref )"
.el .Sh "$dbh\->sqlite_create_function( \f(CW$name\fP, \f(CW$argc\fP, \f(CW$code_ref\fP )"
.IX Subsection "$dbh->sqlite_create_function( $name, $argc, $code_ref )"
This method will register a new function which will be useable in an \s-1SQL\s0
query. The method's parameters are:
.IP "$name" 4
.IX Item "$name"
The name of the function. This is the name of the function as it will
be used from \s-1SQL\s0.
.IP "$argc" 4
.IX Item "$argc"
The number of arguments taken by the function. If this number is \-1,
the function can take any number of arguments.
.IP "$code_ref" 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
\& $dbh->sqlite_create_function( 'now', 0, sub { return time } );
.Ve
.PP
After this, it could be use from \s-1SQL\s0 as:
.PP
.Vb 1
\& INSERT INTO mytable ( now() );
.Ve
.PP
\fI\s-1REGEXP\s0 function\fR
.IX Subsection "REGEXP function"
.PP
SQLite includes syntactic support for an infix operator '\s-1REGEXP\s0', but
without any implementation. The \f(CW\*(C`DBD::SQLite\*(C'\fR driver
automatically registers an implementation that performs standard
perl regular expression matching, using current locale. So for example
you can search for words starting with an 'A' with a query like
.PP
.Vb 1
\& SELECT * from table WHERE column REGEXP '\ebA\ew+'
.Ve
.PP
If you want case-insensitive searching, use perl regex flags, like this :
.PP
.Vb 1
\& SELECT * from table WHERE column REGEXP '(?i:\ebA\ew+)'
.Ve
.PP
The default \s-1REGEXP\s0 implementation can be overriden through the
\&\f(CW\*(C`create_function\*(C'\fR \s-1API\s0 described above.
.PP
Note that regexp matching will \fBnot\fR use SQLite indices, but will iterate
over all rows, so it could be quite costly in terms of performance.
.ie n .Sh "$dbh\->sqlite_create_collation( $name\fP, \f(CW$code_ref )"
.el .Sh "$dbh\->sqlite_create_collation( \f(CW$name\fP, \f(CW$code_ref\fP )"
.IX Subsection "$dbh->sqlite_create_collation( $name, $code_ref )"
This method manually registers a new function which will be useable in an \s-1SQL\s0
query as a \s-1COLLATE\s0 option for sorting. Such functions can also be registered
automatically on demand: see section \*(L"\s-1COLLATION\s0 \s-1FUNCTIONS\s0\*(R" below.
.PP
The method's parameters are:
.IP "$name" 4
.IX Item "$name"
The name of the function exposed to \s-1SQL\s0.
.IP "$code_ref" 4
.IX Item "$code_ref"
Reference to the function's implementation.
The driver will check that this is a proper sorting function.
.ie n .Sh "$dbh\->sqlite_collation_needed( $code_ref )"
.el .Sh "$dbh\->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, $collation_name)
.Ve
.PP
and should register the desired collation using
\&\*(L"sqlite_create_collation\*(R".
.PP
An initial callback is already registered by \f(CW\*(C`DBD::SQLite\*(C'\fR,
so for most common cases it will be simpler to just
add your collation sequences in the \f(CW%DBD::SQLite::COLLATION\fR
hash (see section \*(L"\s-1COLLATION\s0 \s-1FUNCTIONS\s0\*(R" below).
.ie n .Sh "$dbh\->sqlite_create_aggregate( $name\fP, \f(CW$argc\fP, \f(CW$pkg )"
.el .Sh "$dbh\->sqlite_create_aggregate( \f(CW$name\fP, \f(CW$argc\fP, \f(CW$pkg\fP )"
.IX Subsection "$dbh->sqlite_create_aggregate( $name, $argc, $pkg )"
This method will register a new aggregate function which can then be used
from \s-1SQL\s0. The method's parameters are:
.IP "$name" 4
.IX Item "$name"
The name of the aggregate function, this is the name under which the
function will be available from \s-1SQL\s0.
.IP "$argc" 4
.IX Item "$argc"
This is an integer which tells the \s-1SQL\s0 parser how many arguments the
function takes. If that number is \-1, the function can take any number
of arguments.
.IP "$pkg" 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;
.Ve
.PP
.Vb 1
\& sub new { bless [], shift; }
.Ve
.PP
.Vb 2
\& sub step {
\& my ( $self, $value ) = @_;
.Ve
.PP
.Vb 2
\& push @$self, $value;
\& }
.Ve
.PP
.Vb 2
\& sub finalize {
\& my $self = $_[0];
.Ve
.PP
.Vb 1
\& my $n = @$self;
.Ve
.PP
.Vb 2
\& # Variance is NULL unless there is more than one row
\& return undef unless $n || $n == 1;
.Ve
.PP
.Vb 5
\& my $mu = 0;
\& foreach my $v ( @$self ) {
\& $mu += $v;
\& }
\& $mu /= $n;
.Ve
.PP
.Vb 5
\& my $sigma = 0;
\& foreach my $v ( @$self ) {
\& $sigma += ($x - $mu)**2;
\& }
\& $sigma = $sigma / ($n - 1);
.Ve
.PP
.Vb 2
\& return $sigma;
\& }
.Ve
.PP
.Vb 1
\& $dbh->sqlite_create_aggregate( "variance", 1, 'variance' );
.Ve
.PP
The aggregate function can then be used as:
.PP
.Vb 3
\& SELECT group_name, variance(score)
\& FROM results
\& GROUP BY group_name;
.Ve
.PP
For more examples, see the DBD::SQLite::Cookbook.
.ie n .Sh "$dbh\->sqlite_progress_handler( $n_opcodes\fP, \f(CW$code_ref )"
.el .Sh "$dbh\->sqlite_progress_handler( \f(CW$n_opcodes\fP, \f(CW$code_ref\fP )"
.IX Subsection "$dbh->sqlite_progress_handler( $n_opcodes, $code_ref )"
This method registers a handler to be invoked periodically during long
running calls to SQLite.
.PP
An example use for this interface is to keep a \s-1GUI\s0 updated during a
large query. The parameters are:
.IP "$n_opcodes" 4
.IX Item "$n_opcodes"
The progress handler is invoked once for every \f(CW$n_opcodes\fR
virtual machine opcodes in SQLite.
.IP "$code_ref" 4
.IX Item "$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 .Sh "$dbh\->sqlite_commit_hook( $code_ref )"
.el .Sh "$dbh\->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 .Sh "$dbh\->sqlite_rollback_hook( $code_ref )"
.el .Sh "$dbh\->sqlite_rollback_hook( \f(CW$code_ref\fP )"
.IX Subsection "$dbh->sqlite_rollback_hook( $code_ref )"
This method registers a callback function to be invoked whenever a
transaction is rolled back. Any callback set by a previous call to
\&\f(CW\*(C`sqlite_rollback_hook\*(C'\fR is overridden. A reference to the previous
callback (if any) is returned. Registering an \f(CW\*(C`undef\*(C'\fR disables the
callback.
.ie n .Sh "$dbh\->sqlite_update_hook( $code_ref )"
.el .Sh "$dbh\->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, $rowid)
.Ve
.PP
where
.IP "$action_code" 4
.IX Item "$action_code"
is an integer equal to either \f(CW\*(C`DBD::SQLite::INSERT\*(C'\fR,
\&\f(CW\*(C`DBD::SQLite::DELETE\*(C'\fR or \f(CW\*(C`DBD::SQLite::UPDATE\*(C'\fR
(see \*(L"Action Codes\*(R");
.IP "$database" 4
.IX Item "$database"
is the name of the database containing the affected row;
.IP "$table" 4
.IX Item "$table"
is the name of the table containing the affected row;
.IP "$rowid" 4
.IX Item "$rowid"
is the unique 64\-bit signed integer key of the affected row within that table.
.ie n .Sh "$dbh\->sqlite_set_authorizer( $code_ref )"
.el .Sh "$dbh\->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, $trigger_or_view)
.Ve
.PP
where
.IP "$action_code" 4
.IX Item "$action_code"
is an integer that specifies what action is being authorized
(see \*(L"Action Codes\*(R").
.ie n .IP "$string1, $string2" 4
.el .IP "$string1, \f(CW$string2\fR" 4
.IX Item "$string1, $string2"
are strings that depend on the action code
(see \*(L"Action Codes\*(R").
.IP "$database" 4
.IX Item "$database"
is the name of the database (\f(CW\*(C`main\*(C'\fR, \f(CW\*(C`temp\*(C'\fR, etc.) if applicable.
.IP "$trigger_or_view" 4
.IX Item "$trigger_or_view"
is the name of the inner-most trigger or view that is responsible for
the access attempt, or \f(CW\*(C`undef\*(C'\fR if this access attempt is directly from
top-level \s-1SQL\s0 code.
.ie n .Sh "$dbh\->sqlite_backup_from_file( $filename )"
.el .Sh "$dbh\->sqlite_backup_from_file( \f(CW$filename\fP )"
.IX Subsection "$dbh->sqlite_backup_from_file( $filename )"
This method accesses the SQLite Online Backup \s-1API\s0, and will take a backup of
the named database file, copying it to, and overwriting, your current database
connection. This can be particularly handy if your current connection is to the
special :memory: database, and you wish to populate it from an existing \s-1DB\s0.
.ie n .Sh "$dbh\->sqlite_backup_to_file( $filename )"
.el .Sh "$dbh\->sqlite_backup_to_file( \f(CW$filename\fP )"
.IX Subsection "$dbh->sqlite_backup_to_file( $filename )"
This method accesses the SQLite Online Backup \s-1API\s0, and will take a backup of
the currently connected database, and write it out to the named file.
.ie n .Sh "$dbh\->sqlite_enable_load_extension( $bool )"
.el .Sh "$dbh\->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('libsqlitefunctions.so')")
\& or die "Cannot prepare: " . $dbh->errstr();
.Ve
.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>.
.Sh "Authorizer Return Codes"
.IX Subsection "Authorizer Return Codes"
.Vb 3
\& OK
\& DENY
\& IGNORE
.Ve
.Sh "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 34
\& # 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"
.Sh "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.
.Sh "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.
.Sh "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
.Sh "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 $dbh = DBI->connect(
\& "dbi:SQLite:dbname=foo", "", "",
\& {
\& RaiseError => 1,
\& sqlite_unicode => 1,
\& }
\& );
.Ve
.Sh "Adding user-defined collations"
.IX Subsection "Adding user-defined collations"
The native SQLite \s-1API\s0 for adding user-defined collations is
exposed through methods \*(L"sqlite_create_collation\*(R" and
\&\*(L"sqlite_collation_needed\*(R".
.PP
To avoid calling these functions every time a \f(CW$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[àâáäåãçðèêéëìîíïñòôóöõøùûúüý]
\& [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 "TO DO"
.IX Header "TO DO"
The following items remain to be done.
.Sh "Warnings Upgrade"
.IX Subsection "Warnings Upgrade"
We currently use a horridly hacky method to issue and suppress warnings.
It suffices for now, but just barely.
.PP
Migrate all of the warning code to use the recommended \s-1DBI\s0 warnings.
.Sh "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.
.Sh "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.
.Sh "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).
.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>
.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 \- 2009 Adam Kennedy.
.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.