SQL Doesn't Run in the Order You Write It

Mon, 01 Jan 0001 00:00:00 +0000

E very developer who has written SQL has made the same mistake at least once: used a SELECT alias in a WHERE clause, or tried to filter on an aggregate without HAVING, and gotten an error that felt completely arbitrary. It is not arbitrary. It is the database telling you that you wrote the query in one order and expected it to execute in that order. It does not.

Understanding the actual execution order is one of those things that turns SQL from a language you fight into a language you reason with.

SQL Performance Explained

Mon, 01 Jan 0001 00:00:00 +0000

Notes and highlights from reading SQL Performance Explained by Markus Winand.

Sql on Mike Mwita

SQL Doesn't Run in the Order You Write It

SQL Performance Explained