public function addForeignKey($name, $table, $columns, $refTable, $refColumns, $delete = null, $update = null)
    {
        $sql = 'ALTER TABLE ' . $this->db->quoteTableName($table)
            . ' ADD CONSTRAINT ' . $this->db->quoteColumnName($name)
            . ' FOREIGN KEY (' . $this->buildColumns($columns) . ')'
            . ' REFERENCES ' . $this->db->quoteTableName($refTable)
            . ' (' . $this->buildColumns($refColumns) . ')';
        if ($delete !== null) {
            $sql .= ' ON DELETE ' . $delete;
        }
        if ($update !== null) {
            throw new Exception('Oracle does not support ON UPDATE clause.');
        }

        return $sql;
    }
public function addForeignKey($name, $table, $columns, $refTable, $refColumns, $delete = null, $update = null)
    {
        $sql = 'ALTER TABLE ' . $this->db->quoteTableName($table)
            . ' ADD CONSTRAINT ' . $this->db->quoteColumnName($name)
            . ' FOREIGN KEY (' . $this->buildColumns($columns) . ')'
            . ' REFERENCES ' . $this->db->quoteTableName($refTable)
            . ' (' . $this->buildColumns($refColumns) . ')';
        if ($delete !== null) {
            $sql .= ' ON DELETE ' . $delete;
        }
        if ($update !== null) {
            throw new Exception('Oracle does not support ON UPDATE clause.');
        }

        return $sql;
    }
{@inheritdoc}