fix: MySQL comprehensions generated SQL that silently matched nothing - #27
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Ports SPANDigital/cel2sql#177 (and the MySQL half of #169), matching the fix in cel2sql4j. MySQL used the default comprehension source, JSON_TABLE(...) AS x, where a bare reference to x is an unknown column — and the integration catalog skipped every MySQL comprehension case instead of fixing it. Beyond that, the MySQL 8.x optimizer transforms a correlated EXISTS into a semijoin and loses the correlation to JSON_TABLE, so exists()/all() executed without error and matched nothing (works from 9.x; verified against MySQL 8.4.11 and 9.7.1). - MySqlDialect.WriteComprehensionSource renames the value column to the iteration variable through a derived table, the same idiom SqliteDialect already uses for json_each - New IDialect.WriteComprehensionExists/WriteComprehensionNotExists default to EXISTS/NOT EXISTS; MySQL emits COUNT comparisons - The MySQL comprehension skip is removed from the integration catalog, so comp_all/comp_exists/comp_exists_one now execute against the MySQL container in CI - Unit expectations added for all five macros on MySQL
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Ports SPANDigital/cel2sql#177 and the MySQL half of SPANDigital/cel2sql#169, matching SPANDigital/cel2sql4j#44.
The bugs
MySQL used the default comprehension source —
JSON_TABLE(...) AS x— where a bare reference toxis an unknown column (JSON_TABLE is table-valued). The integration catalog skipped every MySQL comprehension case ("comprehension" => dialect.Name != DialectName.MySql) instead of fixing it.Fixing the reference alone isn't enough: the MySQL 8.x optimizer transforms a correlated
EXISTSinto a semijoin and loses the correlation to the JSON_TABLE source, soexists()/all()execute without error and silently match nothing (works from 9.x; verified against 8.4.11 and 9.7.1 locally).The fix
MySqlDialect.WriteComprehensionSource→(SELECT value AS x FROM JSON_TABLE(...) AS jt) AS _t, the derived-table idiomSqliteDialectalready usesIDialect.WriteComprehensionExists/WriteComprehensionNotExists(defaults inDialectBase) with MySQL emitting(SELECT COUNT(*) FROM ...) > 0/= 0comp_all/comp_exists/comp_exists_onenow execute against the MySQL container in CIOther dialects' output is unchanged. Same fix shipped in Go (cel2sql v3.8.10) and Python (pycel2sql v0.4.2); Java is in SPANDigital/cel2sql4j#44.