CASE (Searched)

CASE statements evaluate one or more conditions and return a result when the first condition is met, or a default result if none of the conditions are met.

Sample usage

A common use for CASE is to create new categories or groupings of data. For example, to group selected country values into a Sales Region dimension, you might create a CASE statement like this:

CASE
        WHEN Country IN ("USA","Canada","Mexico") THEN "North America"
        WHEN Country IN ("England","France") THEN "Europe"
        ELSE "Other"
    END

Syntax

CASE
        WHEN condition 
THEN result 
[WHEN condition 
THEN result 
]
        [...]
        [ELSE else_result 
]
    END

Parameters

condition - A logical field or expression. WHEN clauses evaluate condition and return true if the specified condition is met, or false if the condition isn't met.
result - A field or expression of any type. Each WHEN clause must have a matching THEN clause, which specifies the results if that WHEN condition is true. If there are multiple WHEN clauses, the CASE statement returns the result for the first true condition .
else_result (optional) - A field or expression of any type. The ELSE else_result clause specifies a default result for the CASE statement. This clause is returned if none of the WHEN clauses are true. If a CASE statement has no ELSE clause, and none of the WHEN clauses are true, the CASE statement returns NULL .

A CASE statement can have only one ELSE clause.

How searched `CASE` works

A searched CASE statement begins with the CASE keyword and ends with the END keyword. In between, you'll have a number of sections or clauses:

WHEN : A condition that you want to evaluate. You can have multiple WHEN clauses in a single CASE statement.
THEN : The result to return if the WHEN clause's condition is true. You must have one THEN clause for each WHEN clause in your CASE statement.
ELSE : Optional. If none of the WHEN clause conditions are true, CASE returns the value in the ELSE clause, or NULL if no ELSE clause is specified.

CASE evaluates each successive WHEN clause and returns the first result where the condition is true. Any remaining WHEN clauses and the ELSE result are not evaluated. If all WHEN conditions are false or NULL , CASE returns the ELSE result, or if no ELSE clause is present, returns NULL .

Examples

Check for inequality

CASE WHEN Medium != "cpc" THEN "free" ELSE "paid" END

Classify numeric dimension values into discrete buckets

For example, you can separate orders into "Small", "Medium", or "Large" based on order amount:

CASE
        WHEN Amount < 20 THEN "Small"
        WHEN Amount >= 20 and Amount < 100 THEN "Medium"
        WHEN Amount >= 100 THEN "Large"
    END

Classify date dimension values into discrete buckets

For example, you can separate a year into semesters based on specific dates:

CASE
        WHEN Date >= DATE(2018, 9, 23) and Date < DATE(2018, 12, 13) THEN "Fall Semester 2018"
        WHEN Date >= DATE(2018, 1, 3) and Date < DATE(2019, 3, 21) THEN "Winter Semester 2019"
        WHEN Date >= DATE(2019, 3, 27) and Date < DATE(2019, 6, 12) THEN "Spring Semester 2019"
        ELSE "Uncategorized"
    END

Evaluate a logical AND condition

CASE
        WHEN Country ISO Code = "US" AND Medium = "cpc"
        THEN "US - Paid"
        ELSE "other"
    END

Evaluate a logical AND/OR condition

CASE
        WHEN REGEXP_MATCH(Video Title, ".*Google Analytics*")
        AND is_livestream = TRUE
        OR Video Length > 600
        THEN "GA Livestream or long video"
    END

Return a different field or value depending on a parameter value

Example 1: Return a dimension based on the parameter value selected. You can use this technique to let users switch the breakdown dimension used by a chart.

CASE
        WHEN Breakdown = "Product Category" THEN Product Category
        WHEN Breakdown = "Store" THEN Store
    END

You could also write this using simple CASE syntax :

CASE Breakdown
        WHEN "Product Category" THEN Product Category
        WHEN "Store" THEN Store
    END

Example 2: Return a different metric based on a parameter value.

CASE WHEN Show Adjusted Cost = TRUE THEN Cost + Adjustments ELSE Cost END

Nested `CASE` statements

You can nest CASE statements to create more complex branching logic:

CASE WHEN REGEXP_CONTAINS(SKU, "Hats") THEN
        CASE WHEN Color = "blue"
            THEN "BLUE HAT" ELSE "JUST A HAT"
        END
        ELSE "NOT A HAT"
    END