Returns NULL if the operands are equal otherwise returns the first operand
Format
NULLIF( Operand1, Operand2 )
Remarks
This is a shorthand form of the CASE statement.
The expression:
NULLIF(x,y)
is equivalent to:
CASE WHEN x = y THEN NULL ELSE x END
The return value is either NULL or the first operand.
Both Operand1 and Operand2 can be any expression.
Example:
NULLIF( 'Failed', CurrentStateDesc )