CodeIgniter Database Helper to Add and Drop Foreign Keys

CodeIgniter Database Helper to Add and Drop Foreign Keys
https://gist.github.com/natanfelles/4024...9d82dec281

PHP Code:

<?php
/**
 * @author   Natan Felles <[email protected]>
 */
defined('BASEPATH') OR exit('No direct script access allowed');
if ( ! function_exists('add_foreign_key'))
{
    /**
     * @param string $table
     * @param string $foreign_key
     * @param string $references
     * @param string $on_delete
     * @param string $on_update
     *
     * @return string SQL command
     */
    function add_foreign_key($table, $foreign_key, $references, $on_delete = 'RESTRICT', $on_update = 'RESTRICT')
    {
        $constraint = "{$table}_{$foreign_key}_fk";
        $sql = "ALTER TABLE {$table} ADD CONSTRAINT {$constraint} FOREIGN KEY ({$foreign_key}) REFERENCES {$references} ON DELETE {$on_delete} ON UPDATE {$on_update}";
        return $sql;
    }
}
if ( ! function_exists('drop_foreign_key'))
{
    /**
     * @param string $table
     * @param string $foreign_key
     *
     * @return string SQL command
     */
    function drop_foreign_key($table, $foreign_key)
    {
        $constraint = "{$table}_{$foreign_key}_fk";
        $sql = "ALTER TABLE {$table} DROP FOREIGN KEY {$constraint}";
        return $sql;
    }
} 


Must be used in a query, like:

PHP Code:

$fields = array(
    'id'         => [
        'type'           => 'INT(11)',
        'auto_increment' => TRUE,
    ],
    'user_id'    => [
        'type'     => 'INT(11)',
    ],
);
$this->dbforge->add_field($fields);
$this->dbforge->add_key('id', TRUE);
$this->dbforge->create_table($this->table);
$this->db->query(add_foreign_key($this->table, 'user_id', 'users(id)', 'CASCADE', 'CASCADE')); 


and

PHP Code:

$this->db->query(drop_foreign_key($this->table, 'user_id'));
$this->dbforge->drop_table($this->table); 


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