10.11子查询，表连接

--数据转换

select ids,code,name,brand,
(cast(year(time)as varchar(10))+‘年‘
+cast(month(time)as varchar(10))+‘月‘
+cast(day(time)as varchar(10))+‘日‘)as 时间,oil,POWERS,EXHAUST,price ,pic from car
select * from car where ceiling(oil)>=8.0
select * from car where ceiling(oil)>8.0
--子查询

--把查询语句查询出的结果当做一个数值使用或一组数值使用
--all所有的,any任意一个，修饰符
--in（‘‘,‘‘）在数值范围内not in（）不在括号的数值范围内
select price from car where name =‘宝马3系 325i 时尚型‘
select *from car where name like ‘%奥迪%‘and price>=42.38
select *from car where name like ‘%奥迪%‘and price>=(select price from car where name =‘宝马3系 325i 时尚型‘)

select *from car where name like ‘%奥迪%‘and price>(select max(price)from car where name like‘%宝马%‘)
select *from car where name like ‘%奥迪%‘and price>all(select price from car where name like ‘%宝马%‘ )
select *from car where name like ‘%奥迪%‘and price>any(select price from car where name like ‘%宝马%‘ )

--in（‘‘,‘‘）在数值范围内not in（）不在括号的数值范围内 == or的用法
select * from car where brand =‘b001‘or brand =‘b002‘or brand =‘b003‘ 
select * from car where brand in(‘b001‘,‘b002‘,‘b003‘)
select * from car where brand not in(‘b001‘,‘b002‘,‘b003‘)

--表连接  (inner)join on内连接

select* from car
select*from brand 
select code,name,brand,brand_code  from car
 join brand on car.brand =brand .brand_code 
 select code,name,brand,brand_code  from car
 inner join brand on car.brand =brand .brand_code
 select code,name,brand,brand_code  from car
left join brand on car.brand =brand .brand_code
 select code,name,brand,brand_code  from car
 right join brand on car.brand =brand .brand_code
 
 
--子查询
select code,name,(select brand_name from brand where car.brand =brand .brand_code )as brand_name from car 
--表的拼接  用,笛卡尔积,类似for的穷举
select*from car,brand
select*from car,brand where car.brand =brand .brand_code