CASE Function

TheCASEfunction allows you to perform multiple conditional tests on a set of expressions within a single statement. When a test evaluates to true, a corresponding output is generated. Outputs may be a literal or expression.

For more information on the IF function, see IF Function.

Wrangle vs. SQL: This function is part of Wrangle, a proprietary data transformation language. Wrangle is not SQL. For more information, see Wrangle Language.

Basic Usage

Example:

case([ Qty <= 10, 'low_qty', Qty >=100, 'high_qty', 'med_qty'])

Output: Returns a text string based on the evaluation of the Qty column:

Qty <= 10 : low_qty
Qty >= 100 : high_qty
All other values of Qty : med_qty

Syntax and Arguments

In the following, If the testX expression evaluates to true, then the resultX value is the output.

Test expressions are evaluated in the listed order.
Text expressions and results are paired values in an array.
You must include one or more test expressions.
Each test must include a result expression. Result expression can be a literal value or an expression that evaluates to a value of a supported data type.
If a quoted value is included as a test expression, it is evaluated as the value to write for all values that have not yet matched a test (else expression).

case([test1, 'result1',test2, 'result2', testn, 'resultn','result_else'])

Argument	Required?	Data Type	Description
test1, test2, testn	Y	expression	Expression that is evaluated. Must resolve to `true` or `false`
result1, result2, result2, result_else	Y	string	Quoted string that is written if the corresponding test expression evaluates to `true`.

All of these expressions can be constants (strings, integers, or any other supported literal values) or sophisticated elements of logic, although the test expression must evaluate to a Boolean value.

For more information on syntax standards, see Language Documentation Syntax Notes.

test1, test2, testn

These parameters contain the expressions to evaluate. This expression must resolve to a Boolean (true or false) value.

注意

The syntax of a test expression follows the same syntax as the IF function. For example, you must use the double-equals signs to compare values (status == 'Ok').

Usage Notes:

Required?	Data Type	Example Value
Yes	Expression that evaluates to `true` or `false`	(OrderAge > 90)

result1, result2, result2, result_else

If the corresponding test expression evaluates to true, this value is written as the result.

These expressions can literals of any data type or expressions that evaluate to literals of any data type.

Usage Notes:

Required?	Data Type	Example Value
Yes	Literal value or expression	See examples below.

Examples

提示

For additional examples, see Common Tasks.

Example - Basic Usage

The following data represents orders received during the week. Discounts are applied to the orders based on the following rules:

The standard discount is 5%.
If an order is for fewer less than 10 units, then the discount is reduced by 5%.
If an order is for more than 20 units, then the discount is increased by 5%.
The special Friday discount is 2% more than the standard discount.

OrdDate	CustId	Qty	Std_Disc
5/8/17	C001	4	0.05
5/9/17	C002	11	0.05
5/10/17	C003	4	0.05
5/11/17	C001	25	0.05
5/12/17	C002	19	0.05

Transforms:

To determine the day of the week, you can use the following transformation:

Transformation Name	`New formula`
Parameter: Formula type	Single row formula
Parameter: Formula	weekday(Date)

You can build the discount rules into the following transform, which generates the Disc column:

Transformation Name	`New formula`
Parameter: Formula type	Single row formula
Parameter: Formula	case([Qty<10, Std_Disc - 0.05, Qty>=20, Std_Disc + 0.05, weekday_Date == 5, Std_Disc + 0.02, Std_Disc])
Parameter: New column name	'Disc'

Results:

OrdDate	CustId	Qty	Std_Disc	Disc
5/8/17	C001	4	0.05	0
5/9/17	C002	11	0.05	0.05
5/10/17	C003	4	0.05	0
5/11/17	C001	25	0.05	0.1
5/12/17	C002	19	0.05	0.07

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