Comparing multiple tables in mysql
I have 4 tables with the same structure.
This 4 tables are generated from another one, the main table.

 - Main table  -> A (10 000 rows) 
  - table 1 -> a1 (2 000 rows) 
  - table 2 -> a2 (3 000 rows) 
  - table 3 -> a3 (4 000 rows) 
  - table 4 -> a4 (1 000 rows)

It's supposed that 4 generated tables are disjoint, and their sum is equal to table A.

But i need to confirm this.

**My question:** How i compare this 4 tables, to see if they have any id in common? 

I know that i can build a lot of querys to inner join a1 with a2, a1 with a3 and so on.

But i think that should be another better way.
Comparing multiple tables in mysql
===

I have 4 tables with the same structure.
This 4 tables are generated from another one, the main table.

 - Main table  -> A (10 000 rows) 
  - table 1 -> a1 (2 000 rows) 
  - table 2 -> a2 (3 000 rows) 
  - table 3 -> a3 (4 000 rows) 
  - table 4 -> a4 (1 000 rows)

It's supposed that 4 generated tables are disjoint, and their sum is equal to table A.

But i need to confirm this.

**My question:** How i compare this 4 tables, to see if they have any id in common? 

I know that i can build a lot of querys to inner join a1 with a2, a1 with a3 and so on.

But i think that should be another better way.