Interview Q&A / SQL & DBMS
SQL & DBMS interview questions
Joins, keys, normalisation, indexes and transactions for placement and backend interviews.
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- Why can't you use a column alias in the WHERE clause?
WHERE runs before SELECT, so the alias does not exist yet when the filter is evaluated. Repeat the expression, or put the query in a subquery or CTE and filter outside.
BeginnerQuick answer1 min read