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iff()

Applies to: ✅ Microsoft Fabric ✅ Azure Data Explorer ✅ Azure Monitor ✅ Microsoft Sentinel

Returns the then value when the if condition evaluates to true, otherwise it returns the else value.

The iff() and iif() functions are equivalent.

Syntax

iff(if, then, else)

Learn more about syntax conventions.

Parameters

Name	Type	Required	Description
if	string	✔️	An expression that evaluates to a boolean value.
then	scalar	✔️	An expression that returns its value when the if condition evaluates to true.
else	scalar	✔️	An expression that returns its value when the if condition evaluates to false.

Returns

This function returns the then value when the if condition evaluates to true, otherwise it returns the else value.

Example

Run the query

StormEvents
| extend Rain = iff((EventType in ("Heavy Rain", "Flash Flood", "Flood")), "Rain event", "Not rain event")
| project State, EventId, EventType, Rain

Output

The following table shows only the first five rows.

State	EventId	EventType	Rain
ATLANTIC SOUTH	61032	Waterspout	Not rain event
FLORIDA	60904	Heavy Rain	Rain event
FLORIDA	60913	Tornado	Not rain event
GEORGIA	64588	Thunderstorm Wind	Not rain event
MISSISSIPPI	68796	Thunderstorm Wind	Not rain event
...	...	...	...