feat(rules): add W021 having-without-group-by#39
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Pawansingh3889 merged 2 commits intoPawansingh3889:mainfrom May 3, 2026
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Detects HAVING clauses without a preceding GROUP BY in the same statement. The SQL engine treats HAVING-without-GROUP BY as a single implicit group and produces results that surprise the author -- almost always a typo for WHERE. Mirrors the W006 OrderByWithoutLimit pattern: multiline rule, two compiled regexes (HAVING / GROUP BY), check_statement returns a Finding when HAVING appears without GROUP BY (or with GROUP BY appearing after HAVING). Warning severity. Closes Pawansingh3889#3
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Thanks Matt. Fourth contributed rule and the quality bar keeps going up. The depth-aware GROUP BY detection is the right call, and the upfront acknowledgement of the nested-subquery edge case is the kind of disclosure a maintainer always wants to see. Squashing in. |
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Summary
Adds W021, a warning rule that flags
HAVINGwithout a precedingGROUP BYin the same query block. The SQL engine treats this as a single implicit group and produces results that surprise the author -- almost always a typo forWHERE.What changed
sql_guard/rules/warnings.py-- newHavingWithoutGroupByclass. Mirrors W006 (OrderByWithoutLimit) for structure (multiline rule, two compiled regexes,check_statementreturnsFinding | None). Strips line and block comments before matching, and only acceptsGROUP BYmatches at parenthesis depth 0 so aGROUP BYinside a subquery does not satisfy a HAVING in the outer query.sql_guard/rules/__init__.py-- importsHavingWithoutGroupBy, slots it intoALL_RULESbetweenTruncateTable(W020) andCrossJoinExplicit(W022) to fill the W021 gap.tests/fixtures/warnings.sql-- adds the canonicalSELECT total FROM orders HAVING total > 1000;example.tests/test_rules.py-- addstest_w021_having_without_group_by(fixture-driven), plus two unit tests covering the comment and subquery cases. Updates rule-count assertions:test_all_rules_loaded38 → 39,test_28_warningsrenamed totest_29_warningsand bumped 28 → 29 (W-series goes from 22 to 23).Verification
Known limitation
A
SELECT ... FROM (SELECT ... GROUP BY ... HAVING ...) x-- valid SQL where a grouped subquery uses its own HAVING -- can produce a W021 false positive. The rule finds the first HAVING anywhere in the statement and looks for a depth-0 GROUP BY before it; the nested HAVING is depth >0 and its GROUP BY also depth >0, so the depth-0 search misses it. Fixing this cleanly requires depth-aware HAVING/GROUP BY pairing, which is more invasive than W006's regex style and worth a follow-up if it shows up in real fixtures. Filing as-is because the simple form (the one the issue calls out) is correctly detected.Closes #3
This contribution was developed with AI assistance.