Best way to combine multiple advanced MySQL select queries?

To combine multiple advanced MySQL select queries, use UNION. Let us first create a table −

mysql> create table DemoTable1 (Value1 int,Value2 int); Query OK, 0 rows affected (0.62 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1 values(10,29); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1 values(100,190); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable1 values(40,101); Query OK, 1 row affected (0.12 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable1;

This will produce the following output −

+--------+--------+ | Value1 | Value2 | +--------+--------+ | 10     | 29     | | 100    | 190 | | 40     | 101 | +--------+--------+ 3 rows in set (0.00 sec)

Following is the query to create second table −

mysql> create table DemoTable2 (Number1 int, Number2 int); Query OK, 0 rows affected (0.49 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable2 values(100,290); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable2 values(200,390); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable2 values(50,170); Query OK, 1 row affected (0.12 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable2;

This will produce the following output −

+---------+---------+ | Number1 | Number2 | +---------+---------+ | 100     | 290 | | 200     | 390 | | 50     | 170 | +---------+---------+ 3 rows in set (0.00 sec)

Following is the query to combine multiple advanced MySQL select queries −

mysql> (select Value1,Value2 from DemoTable1)    union    (select Number1 AS Value1, Number2 AS Value2 from DemoTable2)    order by Value1 DESC;

This will produce the following output −

+--------+--------+ | Value1 | Value2 | +--------+--------+ | 200    | 390 | | 100    | 290 | | 100    | 190 | | 50     | 170 | | 40     | 101 | | 10     | 29 | +--------+--------+ 6 rows in set (0.04 sec)