数据表更新与删除数据
更新部分数据: UPDATE 表名 SET 字段名1=值1 [字段名2=值2,…] [WHERE 条件表达式]
create database chapter3;
use chapter3;
create table student(
id int(4),
name varchar(20) not null,
grade float
);
insert into student(id,name,grade)
value(1,’zhangsan’,98.5);
update student set id=2,grade=100.0 where name=’zhangsan’;
select *from student where name = ‘ zhangsan’;
更新全部数据:不指定其值就会对指定字段的所有值都更新
删除数据
DELETE FROM 表名 [WHERE 条件表达式]
delete from grade where id=1;
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