Returns NULL if all its arguments evaluate to null. Otherwise, it returns the value of the first non-null argument in the scalar_expression list.
COALESCE is a shorthand expression for the following full CASE expression:
CASE WHEN scalar_expression_1 IS NOT NULL THEN scalar_expression_1 ... WHEN scalar_expression_n IS NOT NULL THEN scalar_expression_n ELSE NULL END
Default Title
The default title for a COALESCE expression appears as:
<CASE expression>