SQL - No Longer Set

QuickTip: Reproducible SELECT Results

Reproducing behavior is the essential first step to debugging problems. Save yourself future SQL debugging headaches with this quick tip.

This ChatGPT prompt lets you easily implement Bill Karwin's clever LEFT JOIN solution to a common data selection problem in SQL.

The DELETE query: a tool for removing records in bulk that is almost too dangerous to use.

The `AS` keyword in SQL allows you to replace table fields with calculated columns while retaining the original name.

A high-performance alternative to subqueries for solving a tricky query problem.

If you apply a WHERE filter directly to the OUTER JOIN side of a query you will effectively turn it into an INNER JOIN.

How do I check thee for NULL? Let me count the ways.

Did you get the error message, "Circular reference caused by alias 'MyField' in query definition's SELECT list"? Don't worry; it's an easy fix!

What's the difference between a RIGHT JOIN and a LEFT JOIN and why use one versus the other?

This improved version of my date-quoting convenience function eliminates a common source of date-handling ambiguity via the ISO date format.

This convenient function generates defensive SQL statements to help you avoid the subtle dangers of the BETWEEN statement when filtering dates.

Let's explore the GROUP BY syntax with an exercise in identifying duplicate records in a Person table.

If you're new to relational databases, the QBE window is the solution to--and cause of--many of your query problems.

Using the BETWEEN clause with date-time fields may lead to unexpected results. There's a safer alternative.