COUNT (Azure Stream Analytics)

 

Updated: October 2, 2017

Applies To: Azure

Returns the number of items in a group. COUNT always returns a bigint data type value.

Syntax

COUNT ( { [ [ALL | DISTINCT] expression ] | * } ) 
  

ALL

Applies the aggregate function to all values. ALL is the default.

DISTINCT

Specifies that COUNT returns the number of unique non-null values.

expression

Is an expression of any type or a column name. Aggregate functions and sub queries are not permitted.

*

Specifies that all events should be counted to return the total number of events in a group. COUNT(*) takes no parameters. COUNT(*) does not require an expression parameter because, by definition, it does not use information about any particular column. COUNT(*) returns the number of events without getting rid of duplicates. It counts each event separately. This includes events that contain null values.

  • COUNT(*) returns the number of events including NULL values and duplicates.

  • COUNT(ALL expression) and COUNT(expression) evaluates expression for each event in a group and returns the number of non-null values.

  • COUNT(DISTINCT expression) evaluates expression for each event in a group and returns the number of unique, non-null values.

  • COUNT(input_stream) is equivalent to COUNT() and COUNT(*), but COUNT(DISTINCT input_stream) counts only unique events.

bigint

SELECT System.TimeStamp AS OutTime, TollId, COUNT(*)   
FROM Input TIMESTAMP BY EntryTime  
GROUP BY TollId, TumblingWindow(minute,3)  
  

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