Day 9 of 14 30 minSubqueriesWITHEXISTS
Break big questions into readable steps. Use a query inside another query, test for existence with EXISTS, and name intermediate results with WITH (common table expressions).
By the end of today you can
- Use a scalar subquery to compare against a computed value
- Filter with IN (subquery) and EXISTS
- Write common table expressions with WITH
- Chain several CTEs into a readable pipeline
- Choose between a join, a subquery and a CTE
What's inside
- 4 sections
- 3 diagrams and mind maps
- 4 code examples you can run
- 4-question quiz
- 1A subquery that returns one value
- 2IN and EXISTS: subqueries that return rows
- 3WITH: name your steps (CTEs)
- 4Which tool when?
Sign in free to read this lesson
Get the full lesson with diagrams, runnable code and the quiz. Your progress is saved across devices.
Sign in free