如何使用MySQL联合合并两个表来创建一个新表？

create table yourTableName
(
   select *from yourTableName1
)
UNioN
(
   select *from yourTableName2
);

mysql> create table Old_TableDemo
   -> (
   -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> UserName varchar(20)
   -> );
Query OK, 0 rows affected (0.63 sec)

mysql> create table Old_TableDemo2
   -> (
   -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> UserName varchar(20)
   -> );
Query OK, 0 rows affected (0.60 sec)

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)

mysql> select *from Old_TableDemo;

+--------+----------+
| UserId | UserName |
+--------+----------+
|      1 | John     |
|      2 | Carol    |
+--------+----------+
2 rows in set (0.00 sec)

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)

mysql> select *from Old_TableDemo2;

+--------+----------+
| UserId | UserName |
+--------+----------+
|      1 | Larry    |
|      2 | Sam      |
+--------+----------+
2 rows in set (0.00 sec)

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

mysql> select *from UserTableDemo;

+--------+----------+
| UserId | UserName |
+--------+----------+
|      1 | John     |
|      2 | Carol    |
|      1 | Larry    |
|      2 | Sam      |
+--------+----------+
4 rows in set (0.00 sec)