如何将相同的id和mrege数据组合成一个记录？

Question

我有一个像这样的数据库结构：

Car
 - id   
 - carname
 - image
 - category
 - status

Parts
 - partid
 - partname

CarParts
 - carpartid
 - carid(fk)
 - partid(fk)
 - amountid(fk)

Category
 - id
 - categoryname

Amount
 - amountid
 - amountvalue

现在正是我正在做的事情：

SELECT * FROM carparts
INNER JOIN car on carparts.carpartid = car.id 

INNER JOIN parts on parts.partid = carparts.carpartid

INNER JOIN amount on amount.amountid = carparts.amountid where status = 1

当carparts表中有多个carpart时，返回重复记录。如何将carparts.id和car.id组合成一行，但仍然有多个partname用于该记录？

Answer 1

试试这个。

SELECT * FROM car left join  carparts on car.id = carparts.carpartid 
left join  parts on parts.partid = carparts.carpartid
left join amount on amount.amountid = carparts.amountid where status = 1
group by car.id

谢谢。

Answer 2

您可以使用：

SELECT group_concat(parts.partname) as parts FROM car left join  carparts on car.id = carparts.carpartid 
left join  parts on parts.partid = carparts.carpartid
left join amount on amount.amountid = carparts.amountid where status = 1
group by car.id

由于我们需要组合记录，我们是通过group by子句来完成的。此外，由于我们需要在一行中有多个记录，因此我们使用group_concat来连接多个结果。 P.S：group_concat返回的值的数量有一些限制吗？