CharlesKWON
63f75bf2bc
Continues the static-analysis sweep from 7babfb7.
--- #3 Resolve NIL ambiguity (HIGH) ---
ResolveFromOuter returned NIL for both "column not found" and
"column value is NULL". Callers tested `xVal != NIL` to decide
success, which silently dropped legitimate NULL outer-row values
in correlated subqueries. Added a by-reference lFound flag so
callers distinguish the two cases.
--- #14 Multi-level LEFT JOIN null-fill (MEDIUM) ---
LEFT JOIN null-fill only fired at the last join level
(`nIdx >= Len(aJoins)`). For `a LEFT JOIN b ON ... JOIN c ON ...`
where b had no match, the null-fill for b was skipped and the
outer row was dropped entirely. Now recurses into subsequent joins
when the match fails, so the base case can still emit a row with
NULLs for b's columns.
--- #18 UNION/INTERSECT/EXCEPT applied after LIMIT (MEDIUM) ---
SQL standard requires set operations before ORDER BY / DISTINCT /
OFFSET / LIMIT. Reordered to:
RIGHT JOIN pass → UNION/INTERSECT/EXCEPT → DISTINCT → ORDER BY
→ OFFSET → LIMIT.
Previously LIMIT clipped the first SELECT before UNION merged the
second's rows, producing more rows than intended.
--- #22 DATEADD month overflow (LOW) ---
`DATEADD('MONTH', 1, '2024-01-31')` produced `SToD("20240231")`
(Feb 31) → empty date. Now normalizes month overflow/underflow
into year rollover and clamps the day to the target month's last
day. Year addition also handles Feb 29 → Feb 28 on non-leap years.
--- #23 VIEW temp file leak (LOW) ---
TSqlIndex:CheckView creates `__view_<table>.dbf` temp files that
were never cleaned up. Added post-scan cleanup in RunSelect's
close section (after CTE cleanup) that erases matching temp files.
Validation:
- FiveSql2 43/43
- Harbour compat 51/51
- go test ./... ALL PASS
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
FiveSql2 — SQL Engine for Harbour DBF/NTX/CDX
Pratt parser + SQL:1992-2023 full standard support Supports both NTX (Clipper) and CDX (FoxPro/ADS) indexes
Architecture
five_SQL("SELECT ...")
│
├── TSqlLexer Tokenizer
├── TSqlParser2 Pratt parser (data-driven operators)
├── TSqlExecutor Query executor (Volcano model)
│ ├── TSqlAlias Central alias manager (no collisions)
│ ├── TSqlIndex NTX/CDX index optimization (auto-detect)
│ ├── TSqlAgg GROUP BY / aggregation
│ ├── TSqlSort ORDER BY / DISTINCT
│ ├── TSqlDDL CREATE/DROP/ALTER TABLE/INDEX
│ └── TSqlTxn BEGIN/COMMIT/ROLLBACK
├── TSqlExpr AST nodes + expression evaluation
└── TSqlFunc 60+ scalar functions
Build & Test
export PATH="/path/to/harbour-core/bin/linux/gcc:$PATH"
export HB_INSTALL_PREFIX="/path/to/harbour-core"
make # Build all tests
make test # Run all 157 tests
make bench # Parser benchmark
make clean # Clean
SQL Standard Coverage
| Standard | Features | Tests |
|---|---|---|
| SQL:1992 | SELECT, JOIN, GROUP BY, HAVING, Subquery, CASE, CAST | 43 |
| SQL:1999 | CTE, Recursive CTE, Window Functions, MERGE | 10 |
| SQL:2003 | SIMILAR TO, GROUPING SETS, LATERAL, Window frames | 64 |
| SQL:2008 | FETCH/OFFSET, FOR UPDATE, Extended MERGE | (incl.) |
| SQL:2016 | JSON functions, LISTAGG | (incl.) |
| SQL:2023 | ANY_VALUE, GREATEST/LEAST, BOOL_AND/OR | (incl.) |
| Challenge | LeetCode-level complex queries | 15 |
| Extreme | Production analytics stress tests | 15 |
Adding New Operators
Edit TSqlParser2.prg, method InitInfixTables():
::hInfixTT[ TK_MYOP ] := { "<=>", 40, 41, ND_BIN }
One line. No structural changes needed.
Copyright
Copyright (c) 2025-2026 Charles KWON (Charles KWON OhJun) Email: charleskwonohjun@gmail.com All rights reserved.