总结
2016-05-27 11:29
155 查看
T-SQL语句
1.创建表
create table CeShi1
(
Uid varchar(50) primary key,
Pwd varchar(50),
Name varchar(50),
Nation varchar(50),
foreign key(Nation) references Nation(Code)
)
primary key 主键
not null 非空
foreign key(Nation) references Nation(Code) 外键
auto_increment 自增长
注意:所有符号必须是英文状态下的
每个表创建完之后加分号
表里面的最后一列写完之后不要加逗号
删除表:
drop table PinPai
数据的操作:CRUD操作
1.添加数据:
insert into Brand values('b001','宝马5'); #第一种方式
insert into Brand (Code) values('b002');#第二种方式
insert into PinPai values('','大众'); #处理自增长列
2.最简单查询
select * from PinPai #查询所有数据
select * from PinPai where Ids = 1;#根据条件查询
3.修改数据
update PinPai set Name = '大众' where Ids = 4; #修改某一条数据
update Car set Name='哈弗',Time='2012-3-4',Price=16,Brand='b002' where Code='c001'
4.删除数据
delete from Brand #删除所有数据
delete from PinPai where Ids = 4; #根据条件删除数据
1.增加内容
insert into Info values('p001','张三',true,'n001','1989-2-3')
insert into Info (Code,Name) values('p002','李四');
2.删除数据
delete from Info where Code = 'p002'
3.修改数据
update Info set Name='李四' where Code='p001'
4.查询数据
(1)简单查询
select * from Info
select Code as '代号',Name as '姓名' from Info
(2)条件查询
select * from Car where Code='c002'
select * from Car where Brand='b001' and Powers=130 或者用or
(3)模糊查询
select * from Car where Name like '%奥迪%' %代表任意多个字符 _代表一个字符
(4)排序查询
select * from Car order by Brand,Powers desc
(5)范围查询
select * from Car where Price>=40 and Price<=60
select * from Car where Price between 40 and 50
(6)离散查询
select * from Car where Code in ('c001','c003','c005','c007')
select * from Car where Code not in('c001','c003','c005','c007')
(7)聚合函数,统计查询
select sum(Price) from Car #查询所有价格之和 sum()求和
select count(Code) from Car #查询数据条数
select max(Code) from Car #求最大值
select min(Brand) from Car #求最小值
select avg(Price) from Car #求平均值
(8)分页查询
#每页显示5条数据,取第2页的数据
select * from Car limit (n-1)*5,5
(9)去重查询
select distinct Brand from Car
(10)分组查询
select count(*),Brand from Car group by Brand
select Brand from Car group by Brand having count(*)>3 #分组之后根据条件查询使用having 不使用where
高级查询
1.连接查询,对列的扩展
select * from Info,Nation #形成笛卡尔积
select Info.Code,Info.Name,Info.Sex,Nation.Name,Info.Birthday from Info,Nation where Info.Nation = Nation.Code
select * from Info join Nation
select * from Info join Nation on Info.Nation = Nation.Code
2.联合查询,对行的扩展
select Code,Name from Info
union
select Code,Name from Nation
3.子查询
(1)无关子查询
外层查询 (里层查询)
子查询的结果当做父查询的条件
子查询:select Code from Nation where Name='汉族'
父查询:select * from Info where Nation = ''
select * from Info where Nation = (select Code from Nation where Name='汉族')
(2)相关子查询
查询汽车表中油耗低于该系列平均油耗的所有汽车信息
父查询:select * from Car where Oil<(该系列平均油耗)
子查询:select avg(Oil) from Car where Brand = '某个系列'
select * from Car a where Oil<(select avg(Oil) from Car b where b.Brand = a.Brand )
1.创建表
create table CeShi1
(
Uid varchar(50) primary key,
Pwd varchar(50),
Name varchar(50),
Nation varchar(50),
foreign key(Nation) references Nation(Code)
)
primary key 主键
not null 非空
foreign key(Nation) references Nation(Code) 外键
auto_increment 自增长
注意:所有符号必须是英文状态下的
每个表创建完之后加分号
表里面的最后一列写完之后不要加逗号
删除表:
drop table PinPai
数据的操作:CRUD操作
1.添加数据:
insert into Brand values('b001','宝马5'); #第一种方式
insert into Brand (Code) values('b002');#第二种方式
insert into PinPai values('','大众'); #处理自增长列
2.最简单查询
select * from PinPai #查询所有数据
select * from PinPai where Ids = 1;#根据条件查询
3.修改数据
update PinPai set Name = '大众' where Ids = 4; #修改某一条数据
update Car set Name='哈弗',Time='2012-3-4',Price=16,Brand='b002' where Code='c001'
4.删除数据
delete from Brand #删除所有数据
delete from PinPai where Ids = 4; #根据条件删除数据
1.增加内容
insert into Info values('p001','张三',true,'n001','1989-2-3')
insert into Info (Code,Name) values('p002','李四');
2.删除数据
delete from Info where Code = 'p002'
3.修改数据
update Info set Name='李四' where Code='p001'
4.查询数据
(1)简单查询
select * from Info
select Code as '代号',Name as '姓名' from Info
(2)条件查询
select * from Car where Code='c002'
select * from Car where Brand='b001' and Powers=130 或者用or
(3)模糊查询
select * from Car where Name like '%奥迪%' %代表任意多个字符 _代表一个字符
(4)排序查询
select * from Car order by Brand,Powers desc
(5)范围查询
select * from Car where Price>=40 and Price<=60
select * from Car where Price between 40 and 50
(6)离散查询
select * from Car where Code in ('c001','c003','c005','c007')
select * from Car where Code not in('c001','c003','c005','c007')
(7)聚合函数,统计查询
select sum(Price) from Car #查询所有价格之和 sum()求和
select count(Code) from Car #查询数据条数
select max(Code) from Car #求最大值
select min(Brand) from Car #求最小值
select avg(Price) from Car #求平均值
(8)分页查询
#每页显示5条数据,取第2页的数据
select * from Car limit (n-1)*5,5
(9)去重查询
select distinct Brand from Car
(10)分组查询
select count(*),Brand from Car group by Brand
select Brand from Car group by Brand having count(*)>3 #分组之后根据条件查询使用having 不使用where
高级查询
1.连接查询,对列的扩展
select * from Info,Nation #形成笛卡尔积
select Info.Code,Info.Name,Info.Sex,Nation.Name,Info.Birthday from Info,Nation where Info.Nation = Nation.Code
select * from Info join Nation
select * from Info join Nation on Info.Nation = Nation.Code
2.联合查询,对行的扩展
select Code,Name from Info
union
select Code,Name from Nation
3.子查询
(1)无关子查询
外层查询 (里层查询)
子查询的结果当做父查询的条件
子查询:select Code from Nation where Name='汉族'
父查询:select * from Info where Nation = ''
select * from Info where Nation = (select Code from Nation where Name='汉族')
(2)相关子查询
查询汽车表中油耗低于该系列平均油耗的所有汽车信息
父查询:select * from Car where Oil<(该系列平均油耗)
子查询:select avg(Oil) from Car where Brand = '某个系列'
select * from Car a where Oil<(select avg(Oil) from Car b where b.Brand = a.Brand )
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