SUM忽略WHERE但不是GROUP BY

Question

我有两个表，adverts和advertsitems。这些表得到了一个（adverts）与很多（advertsitems）的关系。我正在动态构建此查询，因此我使用WHERE 1=1来更容易地添加新条件。

我有以下查询

SELECT a.title AS adtitle, 
     a.id AS adid, 
     a.price, 
     a.image AS image, 
     a.description, 
     SUM(ai.quantity) as quantity, 
     a.shipping, 
     a.customs, 
     a.createdate 
    FROM adverts a 
      LEFT JOIN advertsitems ai 
        ON a.id = ai.advertid 
    WHERE 1=1 
    AND ai.country LIKE '%AF%' 
GROUP BY a.id 
ORDER BY a.id DESC 

的SUM(ai.quantity)结果是2在这种情况下。如果我删除WHERE条件ai.country LIKE，结果为6.我想在两个分离的列中检索这两个值。所以基本上我想要一个SUM忽略的WHERE但不的GROUP BY。

Answer 1

使用条件汇总：

SELECT a.title AS adtitle, a.id AS adid, a.price, a.image AS image, a.description, 
     SUM(ai.quantity) as totalquantity, 
     SUM(case when ai.country LIKE '%AF%' then quantity else 0 end) as AFquantity 
     a.shipping, a.customs, a.createdate, ai.country 
FROM adverts a LEFT JOIN 
    advertsitems ai 
    ON a.id = ai.advertid 
WHERE 1=1 
GROUP BY a.id 
ORDER BY a.id DESC 

如果你真的想按国家过滤，然后用having条款。它会做过滤后聚集：

SELECT a.title AS adtitle, a.id AS adid, a.price, a.image AS image, a.description, 
     SUM(ai.quantity) as totalquantity, 
     SUM(case when ai.country LIKE '%AF%' then quantity else 0 end) as AFquantity 
     a.shipping, a.customs, a.createdate 
FROM adverts a LEFT JOIN 
    advertsitems ai 
    ON a.id = ai.advertid 
WHERE 1=1 
GROUP BY a.id 
HAVING ai.country LIKE '%AF%' 
ORDER BY a.id DESC