需要一个SQL查询

Question

我目前有两张桌子： 汽车（plate_number，品牌，cid） 借用（StartDate，endDate，brand，id）

我想写一个查询，以获取每个品牌的所有可用品牌和可用汽车数量

Answer 1

SELECT c.Brand COUNT(plate_number) FROM car as c LEFT JOIN (borrow as b) on c.cid = b.id WHERE endDate < NOW() GROUP BY c.Brand

我没有尝试，但应该可以。

编辑：修复在哪里。

Answer 2

halfpseudo count行或使用sql count或group by，left join也适用于nullvalues

brand from car join borrow on borrow.brand=car.brand where endDate<currentdate

Answer 3

表格：

car(plate_number, brand, cid)

borrow(StartDate, endDate, brand, id)

select c.plate_number, b.brand, count(b.brand) as available_number
from   car c, borrow b 
where  c.brand=b.brand
       and end_date>=sysdate 
having count(1)>0
group by c.plate_number, b.brand