Question

Hi guys here is my Schema: http://sqlfiddle.com/#!4/82771

CREATE TABLE t1
(
Age INT,
 Name VARCHAR(20)
);

CREATE TABLE t2
(
 Age INT,
 Name VARCHAR(20)
);

INSERT INTO t1(Age, Name) VALUES(31, NULL);
INSERT INTO t1(Age, Name) VALUES(32, NULL);
INSERT INTO t1(Age, Name) VALUES(33, NULL);
INSERT INTO t1(Age, Name) VALUES(34, NULL);

INSERT INTO t2(Age, Name) VALUES(31, 'Panos');

I need a Join query that will give me this Result:

Age    Name
31    'Panos'
32     Null
33     Null
34     Null

I’ve tried LEFT JOIN and RIGHT JOIN on Age but I can’t get what I need. It should be pretty simple but its just not coming to me…

Answer 1

One way is to use union all and then check for non-existence in the second table:

select *
from t1
union all
select *
from t2
where Not exists (select 1 from t1 where t1.age = t2.age)