SQLBuilder\Universal\Query\AlterTableQuery::add PHP Méthode

    public function add($subquery = null)
    {
        if ($subquery) {
            return $this->specs[] = new AlterTableAdd($subquery);
        } else {
            return $this->specs[] = new AlterTableAddConstraint();
        }
    }

 public function testAddForeignKey()
 {
     $q = new AlterTableQuery('products');
     $q->add()->foreignKey('created_by')->references('users', array('id'));
     $q->add()->constraint('fk_updated_by')->foreignKey('updated_by')->references('users', array('id'));
     $this->assertDriverQuery(new MySQLDriver(), $q);
     $this->assertDriverQuery(new PgSQLDriver(), $q);
     $this->assertSqlStrings($q, [[new MySQLDriver(), 'ALTER TABLE `products` ADD FOREIGN KEY (`created_by`) REFERENCES `users` (`id`),' . "\n" . '  ADD CONSTRAINT `fk_updated_by` FOREIGN KEY (`updated_by`) REFERENCES `users` (`id`)']]);
 }