SET SERVEROUTPUT ON;
DECLARE
v_CARE_COUNT NUMBER := 0;
v_PHONE VARCHAr2(40) := NULL;
BEGIN
select count(distinct care_level)
into v_CARE_COUNT
from Table1
where user_id = '100';
IF(v_CARE_COUNT > 0) THEN
select phone into v_PHONE
from Table2
where care_level in
(select distinct care_level from Table1 where user_id = '100')
and rownum = 1;
ELSE
select phone into v_PHONE
from Table2
where care_level = 'default';
END IF;
DBMS_OUTPUT.PUT_LINE('PHONE is <'||v_PHONE||'>');
EXCEPTION
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('Exception : '||SQLERRM);
END;
/
EDIT: ( AS SIngle SQL)
SELECT PHONE
FROM TABLE2
WHERE CARE_LEVEL in
(
SELECT CARE_LEVEL FROM TABLE1 WHERE USER_ID='100'
UNION
SELECT CARE_LEVEL FROM TABLE1 WHERE CARE_LEVEL='default'
AND NOT EXISTS
(SELECT 'X' FROM TABLE1 WHERE USER_ID='100')
)
AND ROWNUM = 1;