Interview Q&A / SQL & DBMS
SQL & DBMS interview questions
Joins, keys, normalisation, indexes and transactions for placement and backend interviews.
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- How do you find rows in one table that have no matching row in another?
Use LEFT JOIN and keep rows where the right table's key IS NULL, or use NOT EXISTS. Both are safer than NOT IN, which fails when the subquery returns a NULL.
IntermediateQuick answerCoding1 min read