CASE WHEN

All functions > CONDITIONAL > CASE WHEN

Returns the result of the first condition that evaluates to true

Syntax

CASE WHEN condition THEN result { WHEN condition THEN result ... } [ ELSE default ] END

Notes

Write this as CASE WHEN … THEN … [ELSE …] END in FeatureQL (same shape as familiar SQL). Conditions are evaluated in order; the first one that is TRUE selects its THEN value.
If no WHEN is TRUE and ELSE is omitted, the result is NULL (typed with the common type of the branch values—use NULL::<type> or typed NULL(...) where inference needs a type).
Evaluation short-circuits: once a condition is TRUE, later branches are not evaluated.
Every THEN expression and the ELSE expression (if present) must be type-compatible.

Related Functions

CASE_WHEN()

Examples

Searched CASE

FeatureQL

SELECT
    -- Second WHEN is first true branch
    f1 := CASE
        WHEN FALSE THEN 1
        WHEN TRUE THEN 2
        WHEN FALSE THEN 3
        ELSE 999
    END,
    -- No WHEN true, ELSE applies
    f2 := CASE
        WHEN FALSE THEN 1
        WHEN FALSE THEN 2
        ELSE 999
    END,
    -- First true branch short-circuits
    f3 := CASE
        WHEN TRUE THEN 1
        WHEN TRUE THEN 2
        ELSE 999
    END,
    -- No match and no ELSE → NULL
    f4 := CASE
        WHEN FALSE THEN 1
        WHEN FALSE THEN 2
    END
;

Result

f1 BIGINT	f2 BIGINT	f3 BIGINT	f4 BIGINT
2	999	1	null

String results

FeatureQL

SELECT
    -- Expression in WHEN
    f1 := CASE
        WHEN 1 = 1 THEN 'yes'
        ELSE 'no'
    END,
    -- First matching inequality
    f2 := CASE
        WHEN 10 > 5 THEN 'big'
        WHEN 10 > 20 THEN 'huge'
        ELSE 'small'
    END,
    -- Single WHEN with ELSE
    f3 := CASE
        WHEN TRUE THEN 42
        ELSE 0
    END
;

Result

f1 VARCHAR	f2 VARCHAR	f3 BIGINT
yes	big	42

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Last update at: 2026/06/20 10:08:10

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