ORDER BY is not analyzed correcly

[lordpretzel]

The analyzer apparently does use column references to the input of the SELECT clause and not the SELECT clause output for ORDER BY expressions. E.g.,

SELECT a, a AS c, b FROM R ORDER BY a,b;

can be used to repeat the problem

[lordpretzel]

Updates

• now we only allow SELECT clause attributes to be used which works correctly
• however, SQL allows for a mix of both, e.g.,

SELECT a+b AS c FROM R ORDER BY c, a

• need to add support for references to FROM entries later