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# Codestriker: Copyright (c) 2001, 2002 David Sitsky.  All rights reserved.

# sits@users.sourceforge.net

#

# This program is free software; you can redistribute it and modify it under

# the terms of the GPL.

package Codestriker::DB::ODBC;

use strict;

use DBI;

use Codestriker;

use Codestriker::DB::Database;

# Module for handling an ODBC database.

@Codestriker::DB::ODBC::ISA = ("Codestriker::DB::Database");

# Type mappings.

my $_TYPE = {

    $Codestriker::DB::Column::TYPE->{TEXT}	=> "ntext",

    $Codestriker::DB::Column::TYPE->{VARCHAR}	=> "nvarchar",

    $Codestriker::DB::Column::TYPE->{INT32}	=> "int",

    $Codestriker::DB::Column::TYPE->{INT16}	=> "smallint",

    $Codestriker::DB::Column::TYPE->{DATETIME}	=> "datetime",

    $Codestriker::DB::Column::TYPE->{FLOAT}	=> "float"

};

# Create a new ODBC database object.

sub new {

    my $type = shift;

    # Database is parent class.

    my $self = Codestriker::DB::Database->new();

    return bless $self, $type;

}

# Return the DBD module this is dependent on.

sub get_module_dependencies {

    return { name => 'DBD::ODBC', version => '0' };

}

# Retrieve a database connection.

sub get_connection {

    my $self = shift;

    # ODBC implementations support transactions, don't enable auto_commit.

    return $self->_get_connection(0, 1);

}

# Return the mapping for a specific type.

sub _map_type {

    my ($self, $type) = @_;

    return $_TYPE->{$type};

}

# Autoincrement type for ODBC.

sub _get_autoincrement_type {

    return "IDENTITY";

}

# Method for retrieving the list of current tables attached to the database.

# For ODBC for SQL SERVER, $dbh->tables doesn't work, need to retrieve data

# from the sysobjects table.

sub get_tables() {

    my $self = shift;

    my @tables = ();

    my $table_select = $self->{dbh}->table_info();

    while (my ($qual, $owner, $table_name, $type, $remarks) =

	   $table_select->fetchrow_array()) {

	push @tables, $table_name;

    }

    $table_select->finish();

    return @tables;

}

# Add a field to a specific table.  If the field already exists, then catch

# the error and continue silently.  The SYNTAX for SQL Server is slightly

# different to standard SQL, there is no "COLUMN" keyword after "ADD".

sub add_field {

    my ($self, $table, $field, $definition) = @_;

    my $dbh = $self->{dbh};

    my $rc = 0;

    eval {

	$dbh->{PrintError} = 0;

	my $field_type = $self->_map_type($definition);

	$dbh->do("ALTER TABLE $table ADD $field $field_type");

	print "Added new field $field to table $table.\n";

	$rc = 1;

	$self->commit();

    };

    if ($@) {

	eval { $self->rollback() };

    }

    $dbh->{PrintError} = 1;

    return $rc;

}

# Indicate if the LIKE operator can be applied on a "text" field.

# For ODBC (SQL Server), this is true.

sub has_like_operator_for_text_field {

    my $self = shift;

    return 1;

}

# Function for generating an SQL subexpression for a case insensitive LIKE

# operation.

sub case_insensitive_like {

    my ($self, $field, $expression) = @_;

    $expression = $self->{dbh}->quote($expression);

    # SQL Server is case insensitive by default, no need to do anything.

    return "$field LIKE $expression";

}

1;