Using variables in DAX

Analysis Services DAX expressions also support using variables to simplify complex expressions by separating a single expression into a series of more easily understood expressions. As previously mentioned, variables also allow a given DAX expression to reuse logic within the same expression, which could improve query performance.

Variables can be defined anywhere in a DAX expression and for any data type, including tables, using the following syntax:

VARIABLENAME = RETURNEDVALUE 

To create a variable definition, use the VAR keyword, as seen in the following code sample:

= VAR 
   SumQuantity = SUM('Internet Sales'[Order Quantity])
RETURN 
   IF(
      SumQuantity > 1000,
      SumQuantity * 0.95,
      SumQuantity * 1.10
   )

A DAX expression can have as many variables as the model author needs. Each variable will...