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iff()

  • Artikkeli

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.

Examples

Classify data using iff()

The following query uses the iff() function to categorize storm events as either "Rain event" or "Not rain event" based on their event type, and then projects the state, event ID, event type, and the new rain category.

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
... ... ... ...

Combine iff() with other functions

The following query calculates the total damage from crops and property, categorizes the severity of storm events based on total damage, direct injuries, and direct deaths, and then summarizes the total number of events and the number of events by severity.

StormEvents
| extend TotalDamage = DamageCrops + DamageProperty
| extend Severity = iff(TotalDamage > 1000000 or InjuriesDirect > 10 or DeathsDirect > 0, "High", iff(TotalDamage < 50000 and InjuriesDirect == 0 and DeathsDirect == 0, "Low", "Moderate"))
| summarize TotalEvents = count(), SeverityEvents = count() by Severity

Output

Severity TotalEvents
Low 54805
High 977
Moderate 3284

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