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NAME
SQL::DB - SQL database interface for Perl (DEPRECATED)
VERSION
0.971.2. Development release.
SYNOPSIS
use SQL::DB ':all';
my $db = SQL::DB->connect( 'dbi:...', 'username', 'password' );
# The very simple stuff
my $success = $db->insert(
into => 'actors',
values => { id => 1, name => 'John Smith' },
);
my $count = $db->update(
'actors',
set => { name => 'Jack Smith' },
where => { id => 1, name => 'John Smith' },
);
my $count = $db->delete(
from => 'actors',
where => { actor_id => 1, last_name => 'Jones' },
);
my $row = $db->select(
[ 'id', 'name' ],
from => 'actors',
where => { id => 1 },
);
print $row->id . ':' . $row->name . "\n";
# The do-any-SQL-you-want stuff
my $people = $db->irow('people');
$db->do(
insert_into => $people->( 'id', 'name' );
sql_values( 1, 'A Name' ),
);
# Anyone celebrating a birthday today gets a raise, with the
# calculation done inside the database.
my $people = $db->urow('people');
$db->do(
update => $people,
set => $people->salary( $people->salary * 2 ),
where => $people->dob == $today,
);
my $purchases = $db->srow('purchases');
my $row = $db->fetch1(
select => [ $people->name, $ps->pid ],
from => $people,
left_join => $purchases,
on => $purchases->id == $people->id,
where => $people->id->in( 1, 2, 3 )
. AND
. $people->name->like('%paul%'),
limit => 1,
offset => 1,
);
# then do stuff with $row->pid, $row->name etc
my @rows = $db->fetch(
select => [ sql_coalesce( $p->pid, $p->cid )->as('pcid') ],
from => $p,
where => $p->cid->is_not_null,
);
# coalesce column is available as $row->pcid
my $iter = $db->iter( @query ... );
while ( my $row = $iter->next ) {
print $row->column(), $row->some_other_column;
}
# If you want the data your own way you can still use the query
# syntax:
my $sth = $db->sth(@query);
map { print join( ',', @$_ ) . "\n" } $sth->fetchall_arrayref;
# Transactions provided by DBIx::Connector
$db->txn(
sub {
# multiple statements
}
);
DESCRIPTION
NOTE: This module is UNSUPPORTED, UNMAINTAINED, and will be REMOVED from
CPAN at the end of 2015. If you found the SQL::DB interface suited your
style of DBI/SQL interaction you may find the DBIx::ThinSQL module a
suitable replacement.
SQL::DB is an extension to the Perl Database Interface (DBI). It is
designed for complicated queries and efficient access to results. With
an API that lets you easily write almost-raw SQL, SQL::DB gives you
unfettered access to the power and flexibility of your underlying
database. It aims to be a tool for programmers who want their databases
to work just as hard as their Perl scripts.
SQL::DB gives you access to aggregate expressions, joins, nested
selects, unions and database-side operator invocations. Transactional
support is provided via DBIx::Connector. Security conscious coders will
be pleased to know that all user-supplied values are bound properly
using DBI "bind_param()". Binding binary data is handled transparently
across different database types.
SQL::DB offers a couple of very simple Create, Retrieve, Update and
Delete (CRUD) action methods. These are designed to get you up and
running quickly when your query data is already inside a hash. The
methods are abstractions of the real API, but should still read as much
as possible like SQL.
Although rows can be retrieved from the database as simple objects,
SQL::DB does not attempt to be an Object-Relational-Mapper (ORM). There
are no auto-inflating columns or automatic joins and the code size and
speed reflect the lack of complexity.
SQL::DB uses the light-weight Log::Any for logging.
QUERY FORMAT
An SQL::DB query is composed from a list of scalars, schema objects,
expressions, and arrays as follows.
Scalars
Scalars are assumed to be SQL keywords and are accepted more or less
unchanged (uppercased with underscores converted to spaces).
Perl SQL
---- ---
'select' SELECT
'outer_join' OUTER JOIN
Schema Objects
and DELETE. A urow object maps to a table in the database. It has a
method for each of the columns in the table which return
column-objects. These column-objects in turn have further methods
which map to various SQL statements. The table and column objects
are used in positions as appropriate for their types.
Perl SQL
---- ---
$table table (for UPDATE statements)
$table table0 (for SELECT statements)
$table->col > 1 table0.col > ?
$table->col->is_not_null table0.col IS NULL
$table->col->asc table0.col ASC
$table->col->between(1,5) table0.col BETWEEN(?,?)
Expressions
Expressions are built using schema objects (described below) that
hold extra information such as table/column names and types, your
application's input values, and their relationships.
Perl SQL
---- ---
$table->col == 1 table0.col = ?
($table->col == 1) .AND.
($table.col2 = ?
$table->col > 1 table0.col > ?
$table->col == table.col =
$table->col2 - $table->col3 table.col2 - table.col3
Arrays
Arrays (array-refs) can contain scalars and expressions which will
appear in the final SQL joined together by commas (',').
Perl SQL
---- ---
select => [1,2,3] SELECT ?,?,?
set => [$t->c1 == 1, $t->c2 == 2 ] SET t->c1 = ?, t.c2 = ?
Functions
Arrays (array-refs) can contain scalars and expressions which will
appear in the final SQL joined together by commas (',').
Perl SQL
---- ---
sql_count($table->col) COUNT(table0.col)
sql_values('a', 'b', 'c') VALUES(?,?,?)
CONSTRUCTORS
new( %args )
Connect to a database and return a new SQL::DB handle. Arguments are
as follows:
dsn The data source name ('dbi:...'). Required.
username
The database authentication username.
password
The database authentication password.
attr
A hash-reference of DBI handle attributes. RaiseError and
AutoCommit are always set to 1 and cannot be overridden.
PrintError defaults to 0. ChopBlanks defaults to 1.
pg_enable_utf8, sqlite_unicode, and mysql_enable_utf8 default to
1.
cache_sth
Whether to use the DBI prepare_cached() method. See ATTRIBUTES
below.
table_info
A reference to a hash containing the table information for the
database. This is typically the value returned from an earlier
call to the "deployed_table_info" method of SQL::DBx::Deploy.
Use of this parameter is not necessary for SQL::DB applications,
but could be an important optimisation to minimize database
calls in applications with more than a trivial number of tables.
This is more interesting for remote database engines such as
PostgreSQL with a higher query latency than for local database
engines such as SQLite.
The standard usage scenario is as follows: After any change to
the table/column structure of the database you can the save
table information to a file:
use SQL::DB;
use SQL::DBx::Deploy;
use YAML::Tiny;
my $db = SQL::DB->connect(...);
DumpFile('table_info.yaml', $db->deployed_table_info);
Then in your application code you set the "table_info" parameter
when you instantiate your SQL::DB object:
package MyApp;
use SQL::DB;
use YAML::Tiny;
my $db = SQL::DB->new(
dsn => 'dbi:Pg:dbname=myapp',
dbuser => 'username',
dbpass => '******',
table_info => LoadFile('table_info.yaml'),
);
Now any calls to "urow" or "srow" on the $db object will not
need to query the database to know the table structure.
connect( $dsn, [ $username, $password, $attr ] )
This is a convenience wrapper around new() for those who prefer
DBI-style construction.
ATTRIBUTES
conn -> DBIx::Connector
The handle connecting us to the database. Read-only.
dbd -> Str
The database driver name (Pg, SQLite, etc). Read-only.
schema -> SQL::DB::Schema
The schema definition associated with this connection. Read-only.
cache_sth <-> Bool
If true then the DBI prepare_cached() method will be used for
creating statement handles. Otherwise prepare() will be used.
METHODS
irows( @tables ) -> @coderef
Returns coderefs for generating table/column strings. Calling the
coderefs with column name arguments returns a string of the form
'table(col1,col2)'.
These refs can be used with the do() method for INSERT queries.
irow( $table ) => &coderef
A singular/scalar version of "irows".
urows( @tables ) -> @URow
Returns schema objects representing database tables/rows for
update-style SQL.
These objects have a method for each table column. Each column
object has the following methods: is_null(), is_not_null(), in(),
not_in(), between(), not_between(), as(), like(), asc(), and desc()
(see SQL::DB::Expr for details).
These objects can be used with the do() method for UPDATE and DELETE
queries.
urow( $table ) => $SQL::DB::Expr
A singular/scalar version of "urows".
srows( @tables ) -> @SRow
Returns schema objects representing database tables/rows for
select-style SQL.
These objects have a method for each table column. Each column
object has the following methods: is_null(), is_not_null(), in(),
not_in(), between(), not_between(), as(), like(), asc(), and desc()
(see SQL::DB::Expr for details).
These objects can be used with the do(), sth(), fetch(), fetch1(),
and iter() methods for SELECT queries.
srow( $table ) => $SQL::DB::Expr
A singular/scalar version of "srows".
prepare( @query ) -> ($sth, $query)
Prepares @query using DBI prepare() and returns a DBI::st statement
handle and the SQL::DB::Expr object representing the query. Croaks
on error.
You need to call execute() on the statement handle yourself
afterwards.
prepare_cached( @query ) -> ($sth, $query)
Prepares @query using DBI prepare_cached() and returns a DBI::st
statement handle and the SQL::DB::Expr object representing the
query. Croaks on error.
You need to call execute() on the statement handle yourself
afterwards.
do(@query) -> $count
Prepares (a INSERT, UPDATE or DELETE) @query using either prepare()
or prepare_cached() (depending on the "cache_sth" attribute) and
execute()'s the associated DBI::st statement handle. Croaks on
error.
Returns the value of the execute() call. The result is typically the
number of rows affected (but this is driver dependent).
sth( @query ) -> DBI::st
Prepares (a SELECT) @query using either prepare() or
prepare_cached() (depending on the "cache_sth" attribute) then
execute()s and returns the associated DBI::st statement handle.
Croaks on error.
This method is useful if you want to obtain the data with one of the
DBI fetchrow_hashref(), fetchall_arrayref() etc methods.
object(@query) -> $object
Prepares (a SELECT) @query using either prepare() or
prepare_cached() (depending on the "cache_sth" attribute) and
execute()'s it. Croaks on error.
Returns a single array-based object and closes the underlying
statement handle. The object has accessor methods for each column
selected.
objects(@query) -> @objects
Prepares (a SELECT) @query using either prepare() or
prepare_cached() (depending on the "cache_sth" attribute) and
execute()'s it. Croaks on error.
Returns a list of array-based objects and closes the underlying
statement handle. Each object has accessor methods for each column
selected.
Be aware that calling this method can consume large amounts of
memory if there are lots of rows to be retrieved. Consider using
iter() instead.
fetch1
An alias for object().
fetch
An alias for objects().
hash
Same as for object() but returns a hashref instead.
hashes
Same as for objects() but returns hashrefs instead.
array
Same as for object() but returns an arrayref instead.
arrays
Same as for objects() but returns arrayrefs instead.
iter( @query ) -> SQL::DB::Iter
Prepares (a SELECT) @query using either prepare() or
prepare_cached() (depending on the "cache_sth" attribute) and
execute()'s it. Croaks on error.
Returns a cursor/iteration object with next() and all() methods for
retrieving array-based objects. Each object has accessor methods for
each column selected.
txn(&coderef)
Runs the Perl code in &coderef as an SQL transaction. If &coderef
does not raise any exceptions then the transaction is commited,
otherwise it is rolled back. See DBIx::Connector for details.
current_timestamp -> Str
Returns the current UTC timestamp as a string in the form
'yyyy-mm-dd hh:mm:ssZ'. The same value is always returned during a
transaction.
query_as_string($sql, @bind_values) -> Str
Pretty print an SQL query by inserting the bind values into the SQL
itself.
insert(into => $table, values => \%val) -> Int
Insert a row into the database and return the number of rows
affected.
update($table, set => \%values, where => \%expr) -> Int
Update rows in the database and return the number of rows affected.
This method is retricted to the wholesale replacement of column
values (no database-side calculations etc). Multiple WHERE
key/values are only 'AND'd together. An 'undef' value maps to SQL's
NULL value.
delete(from => $table, where => \%expr) -> Int
Delete rows from the database and return the number of rows
affected.
select(\@columns, from => $table, where => \%expr) -> @Obj
Retrieve rows from the database as a list of objects in array
context, or a single object in scalar context. These objects
(blessed into a dynamically created class) have an accessor method
for each column.
The first argument to the select() method must be either an array
reference of column names, or a single '*'. If the array reference
is given only the columns specified will be retrieved from the
database.
CLASS FUNCTIONS
The following functions can be exported individually or all at once
using the ':all' tag. They all return an object which can be combined
with or used inside other functions.
bv( $value, [ $bind_type ] ) -> SQL::DB::BindValue
This function returns an object which tells SQL::DB to bind $value
using a placeholder. The optional $bind_type is a database type
(integer, varchar, timestamp, bytea, etc) which will be converted to
the appropriate bind constant during a prepare() or prepare_cached()
call.
query( @query ) -> SQL::DB::Expr
Build an SQL query using a list of scalars, schema objects,
expressions, other functions, and arrays. This function is the basis
for the prepare(), prepare_cached(), do(), sth(), iter(), fetch()
and fetch1() methods.
sql_and( @args ) -> SQL::DB::Expr
Maps to "$arg1 AND $arg2 AND ...".
sql_case( @stmts ) -> SQL::DB::Expr
Wraps @stmts inside a CASE/END pair while converting arguments to
expressions where needed.
sql_case(
when => $actors->name->is_null,
then => 'No Name',
else => $actors->name,
)->as('name')
# CASE WHEN actors0.name IS NULL
# THEN ? ELSE actors0.name END AS name
sql_coalesce(@args) -> SQL::DB::Expr
Maps to "COALESCE($arg1, $arg2, ...)".
sql_cast($arg1, as => $arg2) -> SQL::DB::Expr
Maps to "CAST( $arg1 AS $arg2 )".
sql_concat(@args) -> SQL::DB::Expr
Maps to "$arg1 || $arg2 || ...".
sql_count(@args) -> SQL::DB::Expr
Maps to "COUNT($arg1, $arg2, ...)".
sql_exists(@args) -> SQL::DB::Expr
Maps to "EXISTS(@args)".
sql_func('myfunc', @args) -> SQL::DB::Expr
Maps to "MYFUNC($arg1, $arg2, ...)".
sql_hex(@args) -> SQL::DB::Expr
Maps to "HEX($arg1, $arg2, ...)".
sql_length(@args) -> SQL::DB::Expr
Maps to "LENGTH(@args)".
sql_lower(@args) -> SQL::DB::Expr
Maps to "LOWER(@args)".
sql_ltrim(@args) -> SQL::DB::Expr
Maps to "LTRIM(@args)".
sql_max(@args) -> SQL::DB::Expr
Maps to "MAX(@args)".
sql_min(@args) -> SQL::DB::Expr
Maps to "MIN(@args)".
sql_rtrim(@args) -> SQL::DB::Expr
Maps to "RTRIM(@args)".
sql_sum(@args) -> SQL::DB::Expr
Maps to "MIN(@args)".
sql_or(@args) -> SQL::DB::Expr
Maps to "$arg1 OR $arg2 OR ...".
sql_replace(@args) -> SQL::DB::Expr
Maps to "REPLACE($arg1,$arg2 [,$arg3])".
sql_substr(@args) -> SQL::DB::Expr
Maps to "SUBSTR($arg1, $arg2, ...)".
sql_table($name, @columns) -> SQL::DB::Expr
Maps to "name(col1,col2,...)".
sql_upper(@args) -> SQL::DB::Expr
Maps to "UPPER(@args)".
sql_values(@args) -> SQL::DB::Expr
Maps to "VALUES($arg1, $arg2, ...)".
COMPATABILITY
All SQL::DB releases have so far been DEVELOPMENT!
SQL::DB jumped from version 0.18 to 0.971.2 due to a complete rewrite
based on Moo. Lots of things were simplified, modules deleted,
dependencies removed, etc. The API changed enough to almost give this
distribution a new name, except I don't know of anyone using this apart
from myself. 0.971.2 will be the last release marked as development,
0.99 will be a release candidate, and 1.00 will be the first stable
release.
SEE ALSO
DBIx::Connector, Log::Any
SUPPORT
SQL::DB is managed via Github:
https://github.com/mlawren/sql-db/tree/devel
SQL::DB follows a semantic versioning scheme:
http://semver.org
AUTHOR
Mark Lawrence <nomad@null.net>
COPYRIGHT AND LICENSE
Copyright (C) 2007-2011 Mark Lawrence <nomad@null.net>
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version.
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