mySQL联盟允许非匹配

Question

我想写一个查询，将拉动一些产品信息和照片，如果产品有任何。

select 
    prod.pID, prod.Manufacturer_Name, prod.pUPC, prod.pNum, prod.pPrice, prod.pSalesPrice, prod.pSalesDate, prod.pSalesEndDate, prod.pSale, 
    GROUP_CONCAT(photoName) as photos 
from 
    ds_products as prod 
    inner join ds_photos as pics on pics.objectID=prod.pID 
where 
    pics.photoFlag =2 
group by 
    prod.pID 

问题在于没有照片的产品会被遗漏在结果集之外。我需要添加和/或更改哪些内容才能让没有出现在照片列表中的产品显示在结果中？

感谢

编辑

我试过LEFT JOIN代替内，但得到相同的结果集。如果我只是跑：

select 
    prod.pID, prod.Manufacturer_Name, prod.pUPC, prod.pNum, prod.pPrice, prod.pSalesPrice, prod.pSalesDate, prod.pSalesEndDate, prod.pSale 
from 
    ds_products as prod 

我得到约600k结果。内连接或左连接查询获得约19万个结果。有没有另一种方法来做到这一点？

Answer 1

使用外连接

select 
    prod.pID, prod.Manufacturer_Name, prod.pUPC, prod.pNum, prod.pPrice, prod.pSalesPrice, prod.pSalesDate, prod.pSalesEndDate, prod.pSale, 
    GROUP_CONCAT(photoName) as photos 
from 
    ds_products as prod 
    LEFT join ds_photos as pics on pics.objectID=prod.pID 
where 
    pics.photoFlag =2 OR pics.photoFlag is NULL 
group by 
    prod.pID 

我已经添加了检查photoFlag为null，对于不具备相应的图片 这里的产品的条件正在拨弄：http://sqlfiddle.com/#!2/c2a9c/1/0

欲了解更多信息： http://dev.mysql.com/doc/refman/5.0/en/outer-join-simplification.html

Answer 2

您需要使用LEFT JOIN而不是INNER JOIN这样

select 
    prod.pID, prod.Manufacturer_Name, prod.pUPC, prod.pNum, prod.pPrice, prod.pSalesPrice, prod.pSalesDate, prod.pSalesEndDate, prod.pSale, 
    GROUP_CONCAT(photoName) as photos 
from 
    ds_products as prod 
    LEFT JOIN ds_photos as pics on pics.objectID=prod.pID 
group by 
    prod.pID 

注意我还删除了where子句，因为这是在pics表中查找会限制结果集的值。