return res, err

	case sqlFnSubstring:
		return handleSQLSubstring(r, e.Substring, tableAlias)

	case sqlFnExtract:
		return handleSQLExtract(r, e.Extract, tableAlias)

	case sqlFnTrim:
		return handleSQLTrim(r, e.Trim, tableAlias)

	case sqlFnDateAdd:
		return handleDateAdd(r, e.DateAdd, tableAlias)

	case sqlFnDateDiff:
		return handleDateDiff(r, e.DateDiff, tableAlias)
	}