private function _getTableColumns($tableName)
{
$schema = Db::getInstance()->query("SELECT column_name, data_type, column_default FROM information_schema.columns WHERE table_name = '{$tableName}' ORDER BY ordinal_position")->fetchAll();
$tableColumns = array();
foreach ($schema as $columnInfo) {
$columnName = $columnInfo['column_name'];
$columnDefault = $columnInfo['column_default'];
$columnType = $this->_postgresDataTypeToPhpType($columnInfo['data_type']);
$tableColumns[$columnName] = new DatabaseColumn($columnName, $columnType, $columnDefault);
}
return $tableColumns;
}