如何在 MySQL 中已创建的表中插入 auto_increment?
mysqlmysqli database
使用 ALTER 命令。让我们首先创建一个表 −
mysql> create table DemoTable -> ( -> StudentName varchar(100) -> ); Query OK, 0 rows affected (0.46 sec)
这是插入 auto_increment 的查询 −
mysql> alter table DemoTable ADD COLUMN StudentId int NOT NULL; Query OK, 0 rows affected (0.50 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> alter table DemoTable ADD PRIMARY KEY(StudentId); Query OK, 0 rows affected (1.23 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> alter table DemoTable CHANGE StudentId StudentId int NOT NULL AUTO_INCREMENT; Query OK, 0 rows affected (2.20 sec) Records: 0 Duplicates: 0 Warnings: 0
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable(StudentName) values('Chris');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable(StudentName) values('David');
Query OK, 1 row affected (0.15 sec)
使用 select 语句显示表中的所有记录 −
mysql> select *from DemoTable;
输出
这将产生以下输出 −
+-------------+-----------+ | StudentName | StudentId | +-------------+-----------+ | Chris | 1 | | David | 2 | +-------------+-----------+ 2 rows in set (0.00 sec)
