SQL Efficient Querying: Finding Maximum Values for Each Distinct Value in a Column A high-performance alternative to subqueries for solving a tricky query problem.
SQL SQL Gotcha: When an OUTER JOIN Accidentally Becomes an INNER JOIN If you apply a WHERE filter directly to the OUTER JOIN side of a query you will effectively turn it into an INNER JOIN.
SQL T-SQL ISNULL() vs. VBA IsNull() vs. Jet IS NULL vs. Access VBA Nz() How do I check thee for NULL? Let me count the ways.
SQL Fixing Circular References in Access Queries 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!
SQL When to Use Right Outer Joins in SQL What's the difference between a RIGHT JOIN and a LEFT JOIN and why use one versus the other?
Code Library A Function to Quote Literal Dates When Building SQL in VBA This improved version of my date-quoting convenience function eliminates a common source of date-handling ambiguity via the ISO date format.
Code Library A Safer Alternative to BETWEEN When Filtering Dates This convenient function generates defensive SQL statements to help you avoid the subtle dangers of the BETWEEN statement when filtering dates.
SQL Finding Duplicate People by Date of Birth Let's explore the GROUP BY syntax with an exercise in identifying duplicate records in a Person table.
Basic The QBE Window: Training Wheels for Access Developers If you're new to relational databases, the QBE window is the solution to--and cause of--many of your query problems.
Basic Beware the BETWEEN Using the BETWEEN clause with date-time fields may lead to unexpected results. There's a safer alternative.