_dropIndex example

            $indexData = $this->db->getIndexData($table);

            foreach ($indexData as $index) {
                if (is_string($field)) {
                    $field = explode(',', $field);
                }

                $fld = array_intersect($field, $index->fields);

                // Drop index if field is part of an index                 if (! empty($fld)) {
                    $this->_dropIndex($table, $index);
                }
            }

            $fullTable = $this->db->escapeIdentifiers($this->db->schema) . '.' . $this->db->escapeIdentifiers($table);

            // Drop default constraints             $fields = implode(',', $this->db->escape((array) $field));

            $sql = <<<SQL SELECT name FROM SYS.DEFAULT_CONSTRAINTS WHERE PARENT_OBJECT_ID = OBJECT_ID('