mysql> select * from stu_info1;
+----+----------+------------+-------------+
| id | name | birth | tel |
+----+----------+------------+-------------+
| 1 | ztq | 1994-12-29 | 159****0773 |
| 2 | tqz | 1994-11-27 | 159****0773 |
| 3 | fq | 1994-05-23 | 187****8793 |
| 4 | qf | 1994-05-23 | 187****8793 |
| 5 | 123 | 1998-12-12 | 14 |
| 6 | 12312323 | 1998-12-12 | 14 |
+----+----------+------------+-------------+
mysql> delete from stu_info1 where id = 5;
Query OK, 1 row affected (0.02 sec)
mysql> select * from stu_info1;
+----+----------+------------+-------------+
| id | name | birth | tel |
+----+----------+------------+-------------+
| 1 | ztq | 1994-12-29 | 159****0773 |
| 2 | tqz | 1994-11-27 | 159****0773 |
| 3 | fq | 1994-05-23 | 187****8793 |
| 4 | qf | 1994-05-23 | 187****8793 |
| 6 | 12312323 | 1998-12-12 | 14 |
+----+----------+------------+-------------+
mysql> alter table stu_info1 drop id;
Query OK, 5 rows affected (0.33 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> select * from stu_info1;
+----------+------------+-------------+
| name | birth | tel |
+----------+------------+-------------+
| ztq | 1994-12-29 | 159****0773 |
| tqz | 1994-11-27 | 159****0773 |
| fq | 1994-05-23 | 187****8793 |
| qf | 1994-05-23 | 187****8793 |
| 12312323 | 1998-12-12 | 14 |
+----------+------------+-------------+
5 rows in set (0.00 sec)
mysql> alter table stu_info1
-> add id int unsigned not null auto_increment first, -> add primary key(id); Query OK, 0 rows affected (0.40 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> select * from stu_info1;
+----+----------+------------+-------------+
| id | name | birth | tel |
+----+----------+------------+-------------+
| 1 | ztq | 1994-12-29 | 159****0773 |
| 2 | tqz | 1994-11-27 | 159****0773 |
| 3 | fq | 1994-05-23 | 187****8793 |
| 4 | qf | 1994-05-23 | 187****8793 |
| 5 | 12312323 | 1998-12-12 | 14 |
+----+----------+------------+-------------+
5 rows in set (0.00 sec)
