Empty identifier using Excel column alias syntax causes crash

Detail name	Value
Changelog Number	31378
Type	Bug
Status	Resolved
Affected Versions	Exasol 8.0.0, Exasol 8.29.0, Exasol 2025.1.0, Exasol 2025.2.0, Exasol 2026.1.0
Fix Versions	Exasol 2026.1.1, Exasol 2025.1.14
Resolution Date	2026-08-06

Description

Exasol supports syntax for identifiers for column aliases in the select list delimited by double quotes, following the SQL Standard, and also by single quotes, which is a MS Excel-compatible syntax.

SELECT 1 AS "MY ALIAS";    -- SQL Standard syntax
SELECT 1 AS 'MY ALIAS';    -- MS Excel-compatible syntax

Empty identifiers are not allowed and will give an error:

-- Expected/Observed: Error "illegal zero-length identifier"
SELECT 1 AS "";

However, if a query gives uses the single-quote syntax and the identifier is empty then the session will crash:

-- Expected: Error "illegal zero-length identifier"
-- Observed: Error "Successfully reconnected after internal server error, transaction was rolled back"
SELECT 1 AS '';

-- Expected: Error "illegal zero-length identifier"
-- Observed: Error "Successfully reconnected after internal server error, transaction was rolled back"
SELECT DUMMY AS '' FROM DUAL;

The AS keyword is optional in all of the above queries:

-- Expected: Error "illegal zero-length identifier"
-- Observed: Error "Successfully reconnected after internal server error, transaction was rolled back"
SELECT 'test' '';

Workaround

There is no workaround.

Fix

The query will now return the error “illegal zero-length identifier” as expected, instead of crashing.