SQL question using UNION.

Question

Table and data creation:
CREATE TABLE STATE_HOSPITALS.T1
T1_ID NUMBER(5)
CREATE TABLE STATE_HOSPITALS.T2
T1_ID NUMBER(5),
T2_BALANCE NUMBER(5,2)
CREATE TABLE STATE_HOSPITALS.T3
T1_ID NUMBER(5),
T3_DUE NUMBER(5,2),
T3_ID NUMBER(5)
CREATE TABLE STATE_HOSPITALS.T4
T3_ID NUMBER(5),
T4_AMOUNT NUMBER(5,2)
INSERT INTO STATE_HOSPITALS.T1 (
T1_ID)
VALUES ( 1 );
INSERT INTO STATE_HOSPITALS.T1 (
T1_ID)
VALUES ( 2 );
INSERT INTO STATE_HOSPITALS.T1 (
T1_ID)
VALUES ( 3 );
INSERT INTO STATE_HOSPITALS.T2 (
T1_ID, T2_BALANCE)
VALUES ( 1,250);
INSERT INTO STATE_HOSPITALS.T2 (
T1_ID, T2_BALANCE)
VALUES ( 3,0);
INSERT INTO STATE_HOSPITALS.T3 (
T1_ID, T3_DUE)
VALUES ( 1,10);
INSERT INTO STATE_HOSPITALS.T3 (
T1_ID, T3_DUE)
VALUES ( 2,20);
INSERT INTO STATE_HOSPITALS.T4 (
T3_ID, T4_AMOUNT)
VALUES ( 2,200);
INSERT INTO STATE_HOSPITALS.T4 (
T3_ID, T4_AMOUNT)
VALUES ( 3,300);
I want to use the following query with some correction..
SELECT t1.t1_id,
t2.t2_balance
FROM t1,t2
WHERE t1.t1_ID = t2.t1_id
UNION
SELECT t1.t1_id,
0
FROM t1
WHERE t1.t1_ID IN
( SELECT t1.t1_ID FROM t1, t3
WHERE t1.t1_id = t3.t1_id
AND t3.t3_due <> 0 )
UNION
SELECT t1.t1_ID,
0
FROM t1
WHERE t1.t1_ID IN
( SELECT t1.t1_ID FROM T1, t3,t4
WHERE T1.t1_id = t3.t1_id
AND t3.t3_ID = t4.t3_ID
AND t4.t4_AMOUNT <> 0 );
I want to retrieve as follows
T1_ID T2_BALANCE
==== =======
1     250
2     0
3     0
Thanks.

Answer 1

Hi,
I'm not sure of your requirements.
You can add conditions to Solomon's query, like this:
SELECT    t1.t1_id
,       NVL (t2_balance, 0)     AS t2_balance
FROM                  t1
LEFT OUTER JOIN  t2   ON   t1.t1_id = t2.t1_id
WHERE     t2.t2_balance  > 0
OR       t1.t1_id          IN (
                            SELECT  t1_id
                       FROM     t3
                       WHERE   t3_due     > 0
OR       t1.t1_id          IN (
                            SELECT  t3_id
                       FROM     t4
                       WHERE   t4_amount  > 0
ORDER BY  t1.t1_id
;This gets the results you want:
`    T1_ID T2_BALANCE
         1        250
         2          0
         3          0but so did Solomon's solution. If none of the solutions given so far do what you want, then post some additional sample data that shows where they fail, and explain why you want the results you do in those places.