COALESCE accepts one
or more numeric expressions. The COALESCE function checks the value
of each expression in the order in which they are listed and returns
the first non-null or nonmissing value. If only one value is listed,
then the COALESCE function returns the value of that argument. If
all the values of all expressions are null or missing, then the COALESCE
function returns a null or a missing value depending on whether you
are in ANSI mode or SAS mode.
For
more information, see How FedSQL Processes Nulls and SAS Missing Values.