Turn a deeply nested subquery into a CTE anyone can follow

You open a report you inherited and it takes ten minutes just to work out what it returns.

Beginner to intermediateRead 5 minDoing: half an hour6 steps

What you'll have at the end

The same report rewritten as two or three named CTE steps that read from top to bottom

Before you start

You need

A single report query that already runs and returns correct numbers, built from two or more subqueries nested inside each other.

Not covered

Making the rewritten query run faster is a separate problem from making it readable; this does not touch indexes or execution plans.

Leans on

6 steps

Combine three monthly sales exports into one table with UNION

go there first if the data behind this report is still split across separate monthly exports instead of one queryable table.

Track month over month growth with LAG

once the report reads cleanly from named CTEs, this shows how to add a month-over-month comparison as one more CTE in the same chain.

Checked 26 Aug 2026