CREATE TABLE CUSTOMER (CUSTOMERID INT , ADDRESS VARCHAR(500) , ADDRESSTYPE VARCHAR(25));
INSERT INTO CUSTOMER VALUES (100000001,'ADDRESSA' ,'MAILING ADDRESS');
INSERT INTO CUSTOMER VALUES (100000001,'ADDRESSB', 'REGISTERED ADDRESS');
INSERT INTO CUSTOMER VALUES (100000001, NULL ,'OFFICE ADDRESS');
SELECT
ISNULL(
(SELECT ADDRESS FROM CUSTOMER WHERE CUSTOMERID = 100000001 AND ADDRESSTYPE = 'OFFICE ADDRESS' ) ,
(SELECT ADDRESS FROM CUSTOMER WHERE CUSTOMERID = 100000001 AND ADDRESSTYPE = 'REGISTERED ADDRESS' )
)