MySQL SELECT from two tables with a single query


Use UNION to select from two tables. Let us first create a table −

mysql> create table DemoTable1
(
   Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   FirstName varchar(20)
);
Query OK, 0 rows affected (0.90 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1(FirstName) values('Chris') ;
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable1(FirstName) values('Adam');
Query OK, 1 row affected (0.21 sec)
mysql> insert into DemoTable1(FirstName) values('Sam');
Query OK, 1 row affected (0.16 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable1;

This will produce the following output −

+----+-----------+
| Id | FirstName |
+----+-----------+
|  1 | Chris     |
|  2 | Adam      |
|  3 | Sam       |
+----+-----------+
3 rows in set (0.00 sec)

Following is the query to create second table −

mysql> create table DemoTable2(
   Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   FirstName varchar(20)
);
Query OK, 0 rows affected (1.75 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable2(FirstName) values('John');
Query OK, 1 row affected (0.18 sec)
mysql> insert into DemoTable2(FirstName) values('Tom');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable2(FirstName) values('Bob');
Query OK, 1 row affected (0.50 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable2;

This will produce the following output −

+----+-----------+
| Id | FirstName |
+----+-----------+
|  1 | John      |
|  2 | Tom       |
|  3 | Bob       |
+----+-----------+
3 rows in set (0.00 sec)

Following is the query to select from two tables using MySQL UNION −

mysql> (select *from DemoTable1)
   union
   (select *from DemoTable2)
   order by FirstName;

This will produce the following output −

+----+-----------+
| Id | FirstName |
+----+-----------+
|  2 | Adam      |
|  3 | Bob       |
|  1 | Chris     |
|  1 | John      |
|  3 | Sam       |
|  2 | Tom       |
+----+-----------+
6 rows in set (0.00 sec)
raja
Published on 09-Oct-2019 15:18:25
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