Joins are the core of SQL, and the real signal is precise semantics: semi/anti joins (EXISTS / NOT EXISTS), the NOT IN null trap, and the fan-out bug that quietly doubles your sums.
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Explain SQL join types (inner, left/right/full outer, semi, anti, cross) and when to use each.
Joins are the core of SQL, and the real signal is precise semantics: semi/anti joins (EXISTS / NOT EXISTS), the NOT IN null trap, and the fan-out bug that quietly doubles your sums.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
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