Return Different Values With CASE WHEN

Evaluate conditions row-by-row inside a `SELECT` to produce computed columns based on branching logic.

5/5 supported engines validation-green 1 example 2 scenarios

Docker-validated Not currently validation-green

Example 1

Label order totals as low, medium, or high

Conditions are evaluated in order. Order 1 (30) hits the first branch, order 2 (75) hits the second, and order 3 (300) falls through to ELSE.

Source table data Rows loaded before the example query runs.

Setup

CREATE TABLE orders (id INT, total INT);

INSERT INTO
  orders (id, total)
VALUES
  (1, 30),
  (2, 75),
  (3, 300);

Validated query Shared across supported engines.

SQL

SELECT
  id,
  total,
  CASE
    WHEN total < 50 THEN 'low'
    WHEN total < 200 THEN 'medium'
    ELSE 'high'
  END AS size
FROM
  orders
ORDER BY
  id;

Expected result Returned rows for the shared example.

id	total	size
1	30	low
2	75	medium
3	300	high

Output is identical across all engines.

Useful when

Where this command helps.

bucketing values into labels or ranges
adding derived status text directly in a query result

Explanation

What the command is doing.

CASE WHEN is SQL's conditional expression. Each row is tested against the WHEN conditions in order, and the first matching branch determines the output value. A trailing ELSE catches any rows that do not match any branch. The expression can appear anywhere a value is expected: SELECT, ORDER BY, WHERE, and GROUP BY.

Return Different Values With CASE WHEN

Label order totals as low, medium, or high

Where this command helps.

What the command is doing.

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