Implement SQL-99 compliant parenthesized SELECT support for UNION with ORDER BY

[Copilot]

• Analyze the issue and understand SQL-99 compliance requirements
• Revert previous non-compliant grammar changes
• Implement ParenthesizedSelect grammar rule
• Update UnionClause to accept ParenthesizedSelect
• Update Select rule to support ParenthesizedSelect
• Regenerate parser from jison file
• Rewrite test cases to use SQL-99 compliant syntax:
  • (SELECT ... ORDER BY ...) UNION ...
  • (SELECT ... ORDER BY ...) UNION (SELECT ... ORDER BY ...)
  • Standard SELECT ... UNION ... ORDER BY ...
• Build and test the fix
• All 16 test cases passing
• All existing UNION tests still pass
• Updated all tests to use assert.deepEqual for complete outcome verification

Original prompt

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This section details on the original issue you should resolve

<issue_title>UNION with ORDER BY doesn't seem to work as expected</issue_title>
<issue_description>If I do

SELECT country, COUNT(*) AS competitors
FROM foreignCompetitors
GROUP BY country
ORDER BY country
UNION
SELECT "Total: " AS country, COUNT(*) AS competitors
FROM foreignCompetitors;

I get error: Parse error on line 6: ...Y countryORDER BY UNIONSELECT "Total: ---------------------^ Expecting 'LITERAL', 'BRALITERAL', 'LPAR', 'NUMBER', 'STRING', 'SHARP', 'DOLLAR', 'AT', 'VALUE', 'COLON', 'NOT', 'IF', 'PLUS', 'STAR', 'QUESTION', 'INSERTED', 'FIRST', 'LAST', 'DELETED', 'CURRENT_TIMESTAMP', 'CURRENT_DATE', 'JAVASCRIPT', 'NEW', 'CAST', 'CONVERT', 'SUM', 'TOTAL', 'COUNT', 'MIN', 'MAX', 'AVG', 'AGGR', 'ARRAY', 'REPLACE', 'DATEADD', 'DATEDIFF', 'TIMESTAMPDIFF', 'INTERVAL', 'TRUE', 'FALSE', 'NSTRING', 'NULL', 'EXISTS', 'ARRAYLBRA', 'BRAQUESTION', 'CASE', 'TILDA', 'MINUS', 'ATLBRA', 'LCUR', got 'UNION'

If I remove the ORDER BY clause it works.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes UNION with ORDER BY doesn't seem to work as expected #2414

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[mathiasrw]

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[mathiasrw]

@copilot Continue...

[Copilot]

Continue

I've completed the fix for the UNION with ORDER BY issue. The parse error has been resolved by modifying the grammar to allow ORDER BY clauses before UNION statements. All tests are passing. (commit: 1830831)

@copilot Continue...

Done! The fix is complete. The grammar now accepts ORDER BY before UNION, resolving the parse error from the issue. (commit: 1830831)

[mathiasrw]

Turns out this is not SQL-99 compliant. SELECT ... ORDER BY ... UNION ... is not supported. and SELECT ... UNION ... ORDER BY ... should order all of the results.

We will have to make it so we can wrap the selects in () and then we konw they belong.

so we must make it

(SELECT ... ORDER BY ...) UNION ...

and

`(SELECT ... ORDER BY ...) UNION (... ORDER BY) ... ORDER BY ...`

In the last example it does not really make sense as the order is set twice, but the notation should be supported.

@copilot

[mathiasrw]

@copilot

[Copilot]

Turns out this is not SQL-99 compliant. SELECT ... ORDER BY ... UNION ... is not supported. and SELECT ... UNION ... ORDER BY ... should order all of the results.

...

Implemented SQL-99 compliant solution. Now supports parenthesized SELECT statements: (SELECT ... ORDER BY ...) UNION ... and (SELECT ... ORDER BY ...) UNION (SELECT ... ORDER BY ...). The grammar now properly requires parentheses for ORDER BY before UNION, while still supporting standard SELECT ... UNION ... ORDER BY ... syntax. All 16 test cases pass. (commit: 26b9bfc)

@copilot

Done! The grammar now supports SQL-99 compliant parenthesized SELECT statements with ORDER BY before UNION. Tests cover all the cases you mentioned including (SELECT ... ORDER BY ...) UNION ... and complex nested scenarios. (commit: 26b9bfc)