插入数据
向部门表插入数据:
指定列:
insert into Department(DepartmentName,DepartmentRemark) values('市场部','......')
insert into Department(DepartmentName,DepartmentRemark) values('软件部','......')
insert into Department(DepartmentName,DepartmentRemark) values('企划部','......')
如果部门表只有 (DepartmentName,DepartmentRemark) 两列,则可简写为:
insert into Department values('硬件部','......')
insert into Department values('总经部','......')
insert into Department values('企划部','......')
一次性插入多行数据:
insert into Department(DepartmentName,DepartmentRemark)
select '测试部','......' union
select '实施部','......' union
select '产品部','......'
修改数据
语法:
update 表名 set 字段1=值1,字段2=值2 where 条件
工资调整,每人加薪 1000:
update People set PeopleSalary = PeopleSalary + 1000
将员工编号为 7 的加薪 500:
update People set PeopleSalary = PeopleSalary + 500
where PeopleId = 7
删除数据
语法:
delete from 表名 where 条件
删除员工表所有记录:
delete from People
删除市场部(部门编号3)中工资大于10000 的人:
delete from People where Department = 3 and PeopleSalary > 10000
关于删除(drop、truncate、delete)
drop table People -- 删除表
truncate table People -- 删除所有数据
delete table People -- 删除所有数据
truncate 和 delete 区别:
- truncate 删除所有数据,不能有条件;delete 既可以删除所有数据也可以带条件删除部分数据;
- 假设表中自动编号是 1,2,3, truncate 删除数据后,再次添加数据,编号依然是 1,2,3;delete 删除数据后,再次添加数据,编号从 4,5,6 开始计算。
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