index method
Implementation
@override
void index(ColumnIndex type, String name, List<String> columns) {
if (type == ColumnIndex.indexKey) {
_indexes.add('INDEX `$name` (${columns.map((e) => "`$e`").join(',')})');
} else {
_indexes.add(
'${type.name.toUpperCase()} INDEX `$name` (${columns.map((e) => "`$e`").join(',')})');
}
}