Question

For example we have this 2 tables

table1:

Dir_num |  dir_name
10      | john
11      | vlad

table2:

game    |  dir_num
101     | 10
111     | 10
102     | 11
104     | 10
104     | 10

Now I try to find the dir_name who has less than 2 games played.

select * from table1 where dir_num  ....

Please help me find pl/sql code.

The output should show

 Vlad.

Answer 1

Try something like this — use GROUP BY and HAVING:

SELECT t.dir_num, t.dir_name
FROM Table1 t
  LEFT JOIN Table2 t2 ON t.dir_num = t2.dir_num
GROUP BY t.dir_num, t.dir_name
HAVING COUNT(DISTINCT t2.game) < 2

And here is the SQL Fiddle.

If you want those in both tables (meaning at least 1 game), then change LEFT JOIN to INNER JOIN.

Good luck.