Answer
NULL does not equal anything, even another NULL. Use IS NULL or IS NOT NULL for comparisons.
Quick Answer
NULL is not equal to anything, including itself. col = NULL always evaluates to UNKNOWN (not TRUE or FALSE). WHERE col = NULL never matches any rows. Use IS NULL or IS NOT NULL. In ORDER BY, NULLs appear last in ASC, first in DESC. IFNULL(col, "default") and COALESCE(col, "default") provide substitutes. Most aggregate functions ignore NULLs.
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SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ