fix: keep all clauses when deparsing SELECT without FROM (#2483) - #2484

What

PlainSelect.toString() silently dropped every clause except WHERE / PREWHERE for a SELECT without FROM: GROUP BY, HAVING, WINDOW, QUALIFY, START WITH / CONNECT BY and PREFERRING parsed fine and were stored on the AST, but disappeared from the rendered SQL.

Why

FROM-less SELECT is supported Standard SQL (#1514). A parse -> toString -> reparse round trip silently rewrites the statement, the worst failure mode for audit / rewriting tools. The StatementDeParser path already renders all these clauses unconditionally, so the two render paths disagreed.

How

PlainSelect.appendSelectBodyTo: keep only the FROM-adjacent parts (FROM, lateral views, joins, FINAL, ksql WINDOW) inside the fromItem != null branch, move the shared clause chain out, and delete the truncated else // without from branch. This mirrors SelectDeParser, which already prints the whole chain outside its FROM block. Output for SELECTs with FROM is byte-identical (same checks in the same order).

Root cause

The else // without from branch of PlainSelect.appendSelectBodyTo rendered preWhere / where only, while the whole clause chain sat inside the fromItem != null branch.

Testing

• New regression tests SelectTest#testSelectWithoutFromRetainsWhereGroupByHaving, #testSelectWithoutFromRetainsWindowAndQualify, #testSelectWithoutFromRetainsHierarchicalAndPreferring: on master the round-trip assertions fail (toString() returns SELECT 1), with the fix all pass.
• ./gradlew spotlessApply check: 4858 tests, 0 failures, 0 errors.
• jmh not applicable: deparse-side change only, the parse path and grammar are untouched (same reasoning as fix: complete TablesNamesFinder traversal for piped queries, DML side clauses and analytic functions (#2478) #2479).

Verification of the original issue

On master ad69ecc (jshell, CCJSqlParserUtil.parse(...).toString()):

IN : SELECT 1 GROUP BY 1 HAVING 1=1
OUT: SELECT 1

IN : SELECT 1 WINDOW w AS (ORDER BY 1)
OUT: SELECT 1

IN : SELECT 1 START WITH 1 = 1 CONNECT BY LEVEL <= 1
OUT: SELECT 1

With the fix, all statements from the issue round-trip through both toString() and StatementDeParser (both are asserted by the new tests).

Fixes #2483