Unverified50% confidenceFactExact time
In SQL's three-valued logic, the result of any comparison operation involving NULL is UNKNOWN, rather than TRUE or FALSE.
1
Sources
50%
Confidence
Long-term
Relevance
9/12/2026
First Seen
Sources
Related Entities
Related Claims
UnverifiedIn PostgreSQL, SELECT NULL = NULL returns NULL rather than TRUE.69% similarUnverifiedSqlsure does not rely on another AI model to judge whether SQL is correct or incorrect; instead, it validates SQL semantics in a rule-based, predictable manner.65% similarUnverifiedDECIMAL and NUMERIC are semantically equivalent in standard SQL, both storing numbers precisely in decimal form to avoid the rounding errors of FLOAT/DOUBLE binary floating-point representation.63% similarUnverifiedIf the result of a NOT IN subquery contains any NULL, the entire query returns an empty set; therefore, using NOT EXISTS instead is recommended.62% similarUnverifiedPostgreSQL's aggregate functions ignore NULL values: COUNT(*) counts all rows, while COUNT(val), SUM, and AVG ignore NULL values.61% similar
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