Full join selects all the observations from both data sets but there are missing values where the key value in each observation is found in one table only.
PROC SQL; CREATE TABLE C AS SELECT A.*, B.CC_NUMBER, B.START_DATE FROM CUSTOMER A FULL JOIN CC_DETAILS B ON A.CUSTOMERID=B.CUSTOMERID QUIT;
Dataset C will contain all records from both the tables and fill in
. for missing matches on either side.