case

CASE Expressions in ORDER BY

Sort employees so a specific department appears first, then by salary.

Overview

CASE isn't limited to SELECT — you can use it in ORDER BY to apply custom sorting logic that isn't a simple column order. Here we force the Engineering department to the top of the list regardless of salary, then sort the rest by pay.

The Query

Employees & Departments

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Step-by-Step Breakdown

CASE WHEN d.name = 'Engineering' THEN 0 ELSE 1 END — assigns 0 to Engineering rows and 1 to all others, so Engineering sorts first.
e.salary DESC — the secondary sort, applied within each group.
The two-key ORDER BY produces Engineering (highest paid first), then everyone else (highest paid first).

Multi-key custom sort

You can stack several CASE expressions in ORDER BY to define a fully custom priority without altering the data.

Variations

Sort movies: Sci-Fi first, then newest:

Movies (Movies/Actors/Ratings)

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Common Mistakes

Mismatched THEN types. All THEN/ELSE branches must return the same data type or the CASE errors.
Forgetting the secondary sort. A single CASE in ORDER BY leaves ties unsorted — add a second key.
Assuming it changes values. CASE in ORDER BY only affects ordering, never the returned column values.