分离、附加、备份、还原

--去重

select distinct 列名from表名

--更新

update fenshu set name = ‘李四’where code = 9

--更改表名

sp_rename 表名

drop database 数据库名（删除数据库）drop table 表名

Delete from table where 列 表达式 值

select *from xinxi where fenshu between 80 and 100（两数必需前小后大）

select *from fenshu where name = ‘李四’and nianling = 26

select *from fenshu where name = ‘李四’or nianling = 26

select  *from fenshu where name in(‘李四’,’赵六’)

select  *from fenshu where name not in(‘李四’,’赵六’)

--模糊查询，%表示任意很多字符

select *from fenshu where name like ’%四%’

--下划线表示任意一个字符

select *from fenshu where name like’李_’

--下划线加中括号，等同于in的功能，任意一组满足就能查询出来

select *from fenshu where name like’_[李四，赵六]’

--按年龄排序

select *from fenshu order by nianling asc(默认升序)

select *from fenshu order by nianling desc(降序)

--按降序排列后，查前两名

select top 2 *from fenshu order by nianling desc

--组合排序

*用“,”隔开

select *from score order by Cno asc,Degree desc

--按条件查询后排序。查名字叫李四的人，并选前三高

select top 3 *from fenshu where name = ‘李四’ order by nianling desc

cast(列名 as 数据类型)

*代表所有的，将*改为列名，就能显示该列

ex. select top 1 chinese from xuesheng where class = 1 order by chinese

//查询xuesheng列表中class 1 的 chinese最低成绩

delete from haha where name is null----把名字中含有null的所有数据删掉

update haha set cid = ‘370606198703152121‘ 增加一列数据cid

ex.

create database fenshu

use fenshu

create table study

(

code int,

name varchar(20),

chengji decimal(18,2),

)

go

sp_rename study,xuesheng

alter table xuesheng add [type] varchar

--alter table xuesheng add [type] sysname

--alter table xuesheng drop column [type]

insert into xuesheng values(‘1‘,‘张三‘,‘90‘,‘男‘)

insert into xuesheng (code,name,[type])values(‘2‘,‘李四‘,‘女‘)

insert into xuesheng values(‘3‘,‘王五‘,‘80‘,‘男‘)

select *from xuesheng

select *from xuesheng where name = ‘张三‘