COALESCE Returns the first expression that does not evaluate to BLANK. If all expressions evaluate to BLANK, BLANK is returned.
Syntax
COALESCE(expression, expression[, expression]…)
Parameters
Expression – Any DAX expression that returns a scalar expression.
Return Value
A scalar value coming from one of the expressions or BLANK if all expressions evaluate to BLANK.
Reference Data
https://docs.microsoft.com/en-us/dax/dax-function-reference