MySQL查询替换列值
让我们首先创建一个表-
mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, Score int );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable(Score) values(56); mysql> insert into DemoTable(Score) values(78); mysql> insert into DemoTable(Score) values(34); mysql> insert into DemoTable(Score) values(55);
使用select语句显示表中的所有记录-
mysql> select *from DemoTable;
这将产生以下输出-
+-----------+-------+ | StudentId | Score | +-----------+-------+ | 1 | 56 | | 2 | 78 | | 3 | 34 | | 4 | 55 | +-----------+-------+ 4 rows in set (0.00 sec)
以下是替换列值的查询-
mysql> update DemoTable set Score=95 where StudentId=3; Rows matched : 1 Changed : 1 Warnings : 0
让我们再次检查表记录-
mysql> select *from DemoTable;
这将产生以下输出-
+-----------+-------+ | StudentId | Score | +-----------+-------+ | 1 | 56 | | 2 | 78 | | 3 | 95 | | 4 | 55 | +-----------+-------+ 4 rows in set (0.00 sec)