Compare EXISTS, IN, and JOIN for semi-joins, prevent duplicate customer rows, and handle NULL safely in exclusion queries.
Finding Top Earners: A T-SQL Challenge in SQL Server
The goal is to find the top three highest-paid (top earners) employees in each department and their corresponding department details.
SQL SERVER Challenge – Cumulative Total Calculation
Today we will see a very interesting SQL SERVER Challenge about Cumulative Total Calculation. During a recent Comprehensive Database Performance Health Check.
NOT IN With a NULL in the List Returns No Rows
See why NOT IN with a NULL returns no customers, then compare five sample rows, NOT EXISTS, an IS NOT NULL filter, and query plans.
SQL SERVER – Identifying Query Generating Malicious Wait Type
In this blog post, we will learn about how to fix the performance issue with the malicious Wait Type. Comprehensive Database Performance Health Check
Three-Valued Logic: TRUE, FALSE and UNKNOWN in a WHERE Clause
Understand three-valued logic in WHERE and CHECK, avoid NULL-poisoned NOT IN, and use SQL Server 2022 null-safe comparisons.
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.