Solve relational division with counts and double NOT EXISTS, then handle duplicates, NULL values, empty requirements, and exact matching.
SQL SERVER – Email from Blog Reader – Not a Potential Bug in SQL – Puzzle
A reader was sure he found a severe bug that causes data discrepancy. Run his script and see why it is not a potential bug in SQL Server at all.
SQL SERVER – Correlated and Noncorrelated – SubQuery Introduction, Explanation and Example
What is the difference between correlated and noncorrelated subqueries? I explain both kinds with simple AdventureWorks examples.
SQL SERVER – Fix: Error 130: Cannot perform an aggregate function on an expression containing an aggregate or a subquery
Error 130 says you cannot perform an aggregate function on an expression containing an aggregate, like AVG(COUNT()). A derived table gets around it.
SQL Server Interview Questions and Answers Part 3
Interview Questions and Answers Part 3 opens with NOLOCK: how the hint skips read locks, why that means dirty reads, and what it does for concurrency.