generateDeleteSQL method

Implementation

FutureOr<SQL> generateDeleteSQL(
  Transaction transaction,
  String entityName,
  String table,
  EntityMatcher matcher, {
  Object? parameters,
  List? positionalParameters,
  Map<String, Object?>? namedParameters,
}) {
  var retDeleteSQL = _generateSQLFrom(
    transaction,
    entityName,
    table,
    matcher,
    parameters: parameters,
    positionalParameters: positionalParameters,
    namedParameters: namedParameters,
    sqlBuilder: (String from, EncodingContext context) {
      var tableAlias = context.resolveEntityAlias(table);

      var sql = StringBuffer();
      sql.write('DELETE ');

      if (dialect.acceptsOutputSyntax) {
        sql.write(' OUTPUT DELETED.* ');
      }

      sql.write(from);

      if (dialect.acceptsReturningSyntax) {
        sql.write(' RETURNING "$tableAlias".*');
      }

      return sql.toString();
    },
  );

  if (dialect.acceptsTemporaryTableForReturning &&
      !dialect.acceptsOutputSyntax &&
      !dialect.acceptsReturningSyntax) {
    return retDeleteSQL.resolveMapped((deleteSQL) {
      var conditionSQL = deleteSQL.sqlCondition;

      var tableAlias = deleteSQL.tablesAliases?[table];

      var tmpTable = createTemporaryTableName(table);

      var q = dialect.elementQuote;

      var sqlSelAll = tableAlias != null ? ' $q$tableAlias$q.* ' : '*';
      var sqlAsTableAlias = tableAlias != null ? ' as $q$tableAlias$q ' : '';

      var preSql = SQL(
        'CREATE TEMPORARY TABLE IF NOT EXISTS $q$tmpTable$q AS ('
        ' SELECT $sqlSelAll FROM $q$table$q$sqlAsTableAlias WHERE $conditionSQL '
        ')',
        positionalParameters ?? (parameters is List ? parameters : null),
        namedParameters ??
            (parameters is Map<String, dynamic> ? parameters : null),
        deleteSQL.parametersByPlaceholder,
        mainTable: tmpTable,
      );

      var posSql1 = SQL(
        'SELECT * FROM $q$tmpTable$q',
        [],
        {},
        {},
        mainTable: tmpTable,
      );

      var posSql2 = SQL(
        'DROP TABLE $q$tmpTable$q',
        [],
        {},
        {},
        mainTable: tmpTable,
      );

      deleteSQL = deleteSQL.ensureNotSharedDummy();

      deleteSQL.preSQL = [preSql];
      deleteSQL.posSQL = [posSql1, posSql2];
      deleteSQL.posSQLReturnIndex = 0;

      return deleteSQL;
    });
  }

  return retDeleteSQL;
}