mysql 数据插入insert

mysql> select * from user;
+------+----------+-----------+
| id   | name     | address   |
+------+----------+-----------+
|     | xiaoming | beijing   |
|     | xiaobai  | shandong  |
|     | xiaohong | suzhou    |
|     | xiaohei  | changchun |
+------+----------+-----------+
 rows in set (0.00 sec)

mysql> insert user(id,name,address) values(,"xiaoli","dongjing"),(,"xiaohuang","meiguo");
Query OK,  rows affected (0.01 sec)
Records:   Duplicates:   Warnings: 

mysql> insert user(id,name,address) select id,name,address from user where id=;
Query OK,  row affected (0.01 sec)
Records:   Duplicates:   Warnings: 

mysql> select * from user;
+------+-----------+-----------+
| id   | name      | address   |
+------+-----------+-----------+
|     | xiaoming  | beijing   |
|     | xiaobai   | shandong  |
|     | xiaohong  | suzhou    |
|     | xiaohei   | changchun |
|     | xiaoli    | dongjing  |
|     | xiaohuang | meiguo    |
|     | xiaoming  | beijing   |
+------+-----------+-----------+
 rows in set (0.00 sec)

mysql> insert into user(id,name,address) select id,name,address from user where id=;
Query OK,  rows affected (0.01 sec)
Records:   Duplicates:   Warnings: 

mysql> select * from user;
+------+-----------+-----------+
| id   | name      | address   |
+------+-----------+-----------+
|     | xiaoming  | beijing   |
|     | xiaobai   | shandong  |
|     | xiaohong  | suzhou    |
|     | xiaohei   | changchun |
|     | xiaoli    | dongjing  |
|     | xiaohuang | meiguo    |
|     | xiaoming  | beijing   |
|     | xiaoming  | beijing   |
|     | xiaoming  | beijing   |
+------+-----------+-----------+
 rows in set (0.00 sec)