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How to create a new table from merging two tables with MySQL union?
The following is the syntax to merge two tables using MySQL union
create table yourTableName ( select *from yourTableName1 ) UNION ( select *from yourTableName2 );
To understand the above syntax, let us create a table. The query to create first table is as follows
mysql> create table Old_TableDemo -> ( -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> UserName varchar(20) -> ); Query OK, 0 rows affected (0.63 sec)
The query to create second table is as follows
mysql> create table Old_TableDemo2 -> ( -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> UserName varchar(20) -> ); Query OK, 0 rows affected (0.60 sec)
Insert some records in the first table using insert command. The query is as follows −
mysql> insert into Old_TableDemo(UserName) values('John');
Query OK, 1 row affected (0.22 sec)
mysql> insert into Old_TableDemo(UserName) values('Carol');
Query OK, 1 row affected (0.15 sec)Display all records from the first table using select statement. The query is as follows −
mysql> select *from Old_TableDemo;
The following is the output
+--------+----------+ | UserId | UserName | +--------+----------+ | 1 | John | | 2 | Carol | +--------+----------+ 2 rows in set (0.00 sec)
Now you can insert some records in the second table using insert command. The query is as follows −
mysql> insert into Old_TableDemo2(UserName) values('Larry');
Query OK, 1 row affected (0.22 sec)
mysql> insert into Old_TableDemo2(UserName) values('Sam');
Query OK, 1 row affected (0.10 sec)Display all records from the second table using select statement. The query is as follows −
mysql> select *from Old_TableDemo2;
The following is the output
+--------+----------+ | UserId | UserName | +--------+----------+ | 1 | Larry | | 2 | Sam | +--------+----------+ 2 rows in set (0.00 sec)
Here is the query to create a new table from merging two tables with union
mysql> create table UserTableDemo -> ( -> select *from Old_TableDemo -> ) -> UNION -> ( -> select *from Old_TableDemo2 -> ); Query OK, 4 rows affected (1.18 sec) Records: 4 Duplicates: 0 Warnings: 0
Let us check the table records of new table. The query is as follows −
mysql> select *from UserTableDemo;
The following is the output
+--------+----------+ | UserId | UserName | +--------+----------+ | 1 | John | | 2 | Carol | | 1 | Larry | | 2 | Sam | +--------+----------+ 4 rows in set (0.00 sec)
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