For this, you can use UNION ALL along with LIMIT concept. For our example, we will create three tables.
Let us create the first table −
mysql> create table demo3 −> ( −> value int −> ); Query OK, 0 rows affected (1.39 sec)
Insert some records into the table with the help of insert command −
mysql> insert into demo3 values(10); Query OK, 1 row affected (0.13 sec) mysql> insert into demo3 values(20); Query OK, 1 row affected (0.08 sec) mysql> insert into demo3 values(30); Query OK, 1 row affected (0.08 sec)
Display records from the table using select statement −
mysql> select *from demo3;
This will produce the following output −
+-------+ | value | +-------+ | 10 | | 20 | | 30 | +-------+ 3 rows in set (0.00 sec)
The query to create second table is as follows −
mysql> create table demo4 −> ( −> value1 int −> ); Query OK, 0 rows affected (2.10 sec)
Insert some records into the table with the help of insert command −
mysql> insert into demo4 values(40); Query OK, 1 row affected (0.10 sec) mysql> insert into demo4 values(10); Query OK, 1 row affected (0.09 sec) mysql> insert into demo4 values(60); Query OK, 1 row affected (0.17 sec)
Display records from the table using select statement −
mysql> select *from demo4;
This will produce the following output −
+--------+ | value1 | +--------+ | 40 | | 10 | | 60 | +--------+ 3 rows in set (0.00 sec)
Here is the query to create third table.
mysql> create table demo5 −> ( −> value2 int −> ); Query OK, 0 rows affected (2.13 sec)
Insert some records into the table with the help of insert command −
mysql> insert into demo5 values(100); Query OK, 1 row affected (0.09 sec) mysql> insert into demo5 values(60); Query OK, 1 row affected (0.14 sec) mysql> insert into demo5 values(50); Query OK, 1 row affected (0.10 sec)
Display records from the table using select statement −
mysql> select *from demo5;
This will produce the following output −
+--------+ | value2 | +--------+ | 100 | | 60 | | 50 | +--------+ 3 rows in set (0.00 sec)
Following is the query to limit total number of results across tables −
mysql> select tbl.* −> from ((select * from demo3 ORDER BY value DESC LIMIT 2 −> ) UNION ALL −> (select * from demo4 ORDER BY value1 DESC LIMIT 2 −> ) UNION ALL −> (select * from demo5 ORDER BY value2 DESC LIMIT 2 −> ) −> ) tbl −> −> LIMIT 2;
This will produce the following output −
+-------+ | value | +-------+ | 30 | | 20 | +-------+ 2 rows in set (0.00 sec)