A good query writing strategy starts before you type SELECT: write the question down, find the tables that hold the answer, and build the query one table at a time. This post follows that plan on a small tea shop database with four tables, checks the row count after every join, and confirms the answer by a second route. Every result comes from SQL Server 2025.
SQL SERVER – Not Possible – Delete From Multiple Table – Update Multiple Table in Single Statement
Can you delete from multiple table or update multiple tables in a single statement? No, and you should not try. Here is why, and what a reader pointed out.
INNER HASH JOIN: Why a Table Join Hint Also Fixes Join Order
A join hint in the FROM clause quietly fixes the join order. I show the warning, three plans side by side, and the softer query-level alternative.
Modeling Friends and Followers With SQL Server Graph Tables
Build SQL Server graph tables for follows, mutual connections and friends of friends, then use shortest paths and compare a junction table.
Triangular Joins: The Hidden Row Explosion in Self-Joins
A small grouped result can hide a huge pile of row pairs. Here is how to count them and what to do instead.
SQL SERVER – Solution Part 2 – A Quick Puzzle on SQL JOIN and NULL – SQL Brain Teaser
Part 2 of the solution to my puzzle on SQL Join and NULL. Readers still email me answers every day, so here are more of the good ones they sent.
SQL SERVER – INNER JOIN Returning More Records than Exists in Table
Can an INNER JOIN returning more records than exist in a table be right? Jeff thought it was a bug. Our chat shows why it is possible and natural.