Mysql中update的用法

update修改表数据

语法格式：

update 表名 set 字段名1=值1,字段名2=值2...where 条件；

注意：没有条件整张表数据全部更新

部门表更新实例

mysql> update dept set loc = 'shanghai', dname = 'renshibu' where deptno = 10;
Query OK, 0 rows affected (0.01 sec)
Rows matched: 1  Changed: 0  Warnings: 0

mysql> select * from dept
+--------+------------+----------+
| deptno | dname      | loc      |
+--------+------------+----------+
|     10 | renshibu   | shanghai |
|     20 | RESEARCH   | DALLAS   |
|     30 | SALES      | CHICAGO  |
|     40 | OPERATIONS | BOSTON   |
+--------+------------+----------+
4 rows in set (0.00 sec)

不加where语句，默认全部更新

mysql> update dept set loc = 'shanghai', dname = 'renshibu';
Query OK, 3 rows affected (0.00 sec)
Rows matched: 4  Changed: 3  Warnings: 0

mysql> select * from dept;
+--------+----------+----------+
| deptno | dname    | loc      |
+--------+----------+----------+
|     10 | renshibu | shanghai |
|     20 | renshibu | shanghai |
|     30 | renshibu | shanghai |
|     40 | renshibu | shanghai |
+--------+----------+----------+
4 rows in set (0.00 sec)