as operator

Learn how to use the as operator to bind a name to the operator’s input tabular expression.

Binds a name to the operator’s input tabular expression. This operator allows the query to reference the value of the tabular expression multiple times without breaking the query and binding a name through the let statement.

To optimize multiple uses of the as operator within a single query, see Named expressions.

Syntax

T | as [hint.materialized = Materialized] Name

Parameters

Name	Type	Required	Description
T	`string`	✔️	The tabular expression to rename.
Name	`string`	✔️	The temporary name for the tabular expression.
`hint.materialized`	`bool`		If Materialized is set to `true`, the value of the tabular expression output is wrapped by a materialize() function call. Otherwise, the value is recalculated on every reference.

Examples

In the following two examples, the generated TableName column consists of ‘T1’ and ‘T2’.

range x from 1 to 5 step 1 
| as T1 
| union withsource=TableName (range x from 1 to 5 step 1 | as T2)

Alternatively, you can write the same example as follows:

union withsource=TableName (range x from 1 to 5 step 1 | as T1), (range x from 1 to 5 step 1 | as T2)

Output

TableName	x
T1	1
T1	2
T1	3
T1	4
T1	5
T2	1
T2	2
T2	3
T2	4
T2	5

In the following example, the ’left side’ of the join is: MyLogTable filtered by type == "Event" and Name == "Start" and the ‘right side’ of the join is: MyLogTable filtered by type == "Event" and Name == "Stop"

MyLogTable  
| where type == "Event"
| as T
| where Name == "Start"
| join (
    T
    | where Name == "Stop"
) on ActivityId

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