Databases

🧮 Sets and functions

Combine queries with UNION, INTERSECT and EXCEPT; handle NULL with COALESCE and three-valued logic; transform data with scalar and aggregate functions.

What you'll learn

Combine results from several queries with UNION, UNION ALL, INTERSECT and EXCEPT
Replace and handle null values with COALESCE, IFNULL and NULLIF
Transform text with scalar functions (UPPER, LOWER, SUBSTR, TRIM, ||)
Apply numeric and aggregate functions such as ROUND and GROUP_CONCAT

Lessons

Set operationsCombining the result of two queries: UNION, INTERSECT and EXCEPT. Working with NULLCOALESCE, IFNULL, NULLIF and three-valued logic. Scalar and aggregate functionsStrings, numbers, GROUP_CONCAT and date functions.

Practice this module in the app

DevPath is a hands-on course: you read the theory here; in the app you put it into practice with exercises that really run, offline.

Start free in the app →