Extend support of SELECT without FROM

Detail name	Value
Changelog Number	16196
Type	Improvement
Status	Resolved
Fix Versions	Exasol 8.9.0, Exasol 7.1.21
Resolution Date	2023-02-02

Background

SELECT 1 is a short way to write SELECT 1 FROM DUAL in Exasol.
Until this improvement, the short notation had several limitations.

For example, the following queries did not work :

SELECT 1 WHERE TRUE;
SELECT * WHERE TRUE;
SELECT LEVEL CONNECT BY LEVEL < 10 START WITH LEVEL >= 0;
SELECT SUM(1) GROUP BY NULL;
SELECT 1 HAVING TRUE;
SELECT 1 PREFERRING LOW 1;
SELECT SUM(1) OVER w WINDOW w AS (PARTITION BY 1);
SELECT 1 QUALIFY TRUE;

Adding FROM DUAL to the query would let the queries run.

Improvement

Queries without FROM DUAL are supported and work as expected.