DBIx::SQLEngine::Driver::Trait::PerlDBLib - For use with SQL::Statement
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NAME
DBIx::SQLEngine::Driver::Trait::PerlDBLib - For use with SQL::Statement
SYNOPSIS
# Classes can import this behavior if they're based on SQL::Statement
use DBIx::SQLEngine::Driver::Trait::PerlDBLib ':all';
DESCRIPTION
This package works with DBD drivers which are implemented in Perl using SQL::Statement. It combines several other traits and methods which can be shared by most such drivers.
About Driver Traits
You do not need to use this package directly; it is used internally by those driver subclasses which need it.
For more information about Driver Traits, see "About Driver Traits" in DBIx::SQLEngine::Driver.
REFERENCE
The following methods are provided:
fetch_one_value
Special handling for simple functions. Allows select count(), max(), or min(), but only if that is the only value being returned.
sql_limit
Adds support for SQL select limit clause.
TODO: Needs workaround to support offset.
do_insert_with_sequence
$sqldb->do_insert_with_sequence( $sequence_name, %sql_clauses ) : $row_count
Implemented using DBIx::SQLEngine::Driver::Trait::NoSequences.
detect_any
$sqldb->detect_any ( ) : $boolean
Returns 1, as we presume that the requisite driver modules are
available or we wouldn't have reached this point.
sql_detect_any
This should not be called. Throws fatal exception.
sql_create_columns
$sqldb->sql_create_columns( $column, $fragment_array_ref ) : $sql_fragment
Generates the SQL fragment to define a column in a create table statement.
Overridden to not produce "PRIMARY KEY ( foo )" clauses for the primary key.
dbms_create_column_types
$sqldb->dbms_create_column_types () : %column_type_codes
Implemented using the standard int and varchar types.
dbms_create_column_text_long_type
$sqldb->dbms_create_column_text_long_type () : $col_type_str
Implemented using the standard varchar type.
dbms_select_table_as_unsupported
$sqldb->dbms_select_table_as_unsupported () : 1
Capability Limitation: This driver does not support table aliases such as "select * from foo as bar".
dbms_column_types_unsupported
$sqldb->dbms_column_types_unsupported () : 1
Capability Limitation: This driver does not store column type information.
dbms_indexes_unsupported
$sqldb-> dbms_indexes_unsupported () : 1
Capability Limitation: This driver does not support indexes.
dbms_storedprocs_unsupported
$sqldb-> dbms_storedprocs_unsupported () : 1
Capability Limitation: This driver does not support stored procedures.
SEE ALSO
See DBIx::SQLEngine for the overall interface and developer documentation.
See DBIx::SQLEngine::Docs::ReadMe for general information about
this distribution, including installation and license information.
See DBIx::Sequence for another version of the sequence-table functionality, which greatly inspired this module.
########################################################################
package DBIx::SQLEngine::Driver::Trait::PerlDBLib;
use strict;
use Carp;
use vars qw( @EXPORT_OK %EXPORT_TAGS );
########################################################################
use DBIx::SQLEngine::Driver::Trait::NoUnions ':all';
use DBIx::SQLEngine::Driver::Trait::NoSequences ':all';
use DBIx::SQLEngine::Driver::Trait::NoColumnTypes ':all';
use DBIx::SQLEngine::Driver::Trait::NoAdvancedFeatures qw( :all );
use Exporter;
sub import { goto &Exporter::import }
@EXPORT_OK = (
qw(
fetch_one_value sql_limit
detect_any sql_detect_any
dbms_create_column_types dbms_create_column_text_long_type
sql_create_columns
dbms_select_table_as_unsupported
),
@DBIx::SQLEngine::Driver::Trait::NoUnions::EXPORT_OK,
@DBIx::SQLEngine::Driver::Trait::NoSequences::EXPORT_OK,
@DBIx::SQLEngine::Driver::Trait::NoColumnTypes::EXPORT_OK,
@DBIx::SQLEngine::Driver::Trait::NoAdvancedFeatures::EXPORT_OK,
);
%EXPORT_TAGS = ( all => \@EXPORT_OK );
########################################################################
########################################################################
sub fetch_one_value {
my $self = shift;
my %args = @_;
if ( my $column_clause = $args{columns} ) {
if ( $column_clause =~ /\A\s*count\((.*?)\)\s*\Z/ ) {
$args{columns} = $1;
my $rows = $self->fetch_select( %args );
return( $rows ? scalar( @$rows ) : 0 )
} elsif ( $column_clause =~ /\A\s*max\((.*?)\)\s*\Z/ ) {
$args{columns} = $1;
$args{order} = "$1 desc";
} elsif ( $column_clause =~ /\A\s*min\((.*?)\)\s*\Z/ ) {
$args{columns} = $1;
$args{order} = "$1";
}
}
$self->NEXT('fetch_one_value', %args );
}
########################################################################
sub sql_limit {
my $self = shift;
my ( $limit, $offset, $sql, @params ) = @_;
# You can't apply "limit" to non-table fetches
$sql .= " limit $limit" if ( $sql =~ / from / );
return ($sql, @params);
}
########################################################################
########################################################################
sub detect_any {
return 1;
}
sub sql_detect_any {
croak "Unsupported";
}
########################################################################
# Filter out primary key clauses in SQL create statements
sub sql_create_columns {
my($self, $table, $column, $columns) = @_;
return if ( $column->{type} eq 'primary' );
$self->NEXT('sql_create_columns', $table, $column, $columns );
}
sub dbms_create_column_types {
'sequential' => 'int',
}
sub dbms_create_column_text_long_type {
'varchar(16384)'
}
########################################################################
sub dbms_select_table_as_unsupported { 1 }
########################################################################
########################################################################
1;