Question

I have the following problem. I have 2 tables in the database – table1 and table2.

Table1
id| val1| val2
--------------
1 | 234 | 342
2 | 325 | 356
...

Table2
id | uid | val 
--------------
1  | 5   | 234
2  | 6   | 362
3  | 5   | 123

I would like to check for each record in table2 if val exists in table1 (table2.val=table1.va1 or table2.val > table1.vall).
In table1 is about 2 million records. In table2 several thousand.
If query result true i’d like to remove rows from table2.

Is it possible to do this in one query? mysql or postgresql

Performance is very important.

Answer 1

Assuming (t2.val = t1.val1) or (t1.val2 > t2.val) conditions:

delete table2
from table2 t2
inner join table1 t1 on (t2.val = t1.val1) or (t1.val2 > t2.val)