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What is Left Anti Join and its use case?

SQLmedium0.6 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Altimetrik
Key Concepts Tested
join
Expert AnswerPremium
122 wordsInterview-ready
Left Anti Join returns rows from the left table that have NO match in the right table. Implementation: SELECT a.* FROM table_a a LEFT JOIN table_b b ON a.id = b.id WHERE b.id IS NULL. Or NOT EXISTS: SELECT * FROM a WHERE NOT EXISTS (SELECT 1 FROM b WHERE b.id = a.id). Use cases: Find customers who never ordered; records in source but not target (data reconciliation); exclusion logic. Best practice: NOT EXISTS often optimizes better than LEFT JOIN + NULL....
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