MySQL Group不在子查詢中工作

Question

我有這個查詢，效果很好。 我使用MIN(home_price)顯示作為起始價格，我使用此查詢為api和WHERE子句添加到它，所以如果我按價格搜索MIN(home_price)更改。

SELECT MIN(home_price) as min_home_price,
   id,
   name,
   community,
   maplocation,
   locationLabel,
   logo 
FROM ourCommunity 
INNER JOIN readyBuilt 
   ON community = home_community 
INNER JOIN rb_locations 
   ON readyBuilt.home_location = rb_locations.locationId 
WHERE id IN ( SELECT DISTINCT id 
                 FROM ourCommunity 
                 INNER JOIN readyBuilt 
                        ON community = home_community 
                 WHERE isDeleted = 0 AND is_upcoming = 0) 
   AND home_status = 1 
 GROUP BY id,name,community,mapLocation,locationLabel,logo 
 ORDER BY name

所以我的解決方案是使用子查詢

SELECT id,
   name,
   community,
   maplocation,
   locationLabel,
   logo, 
   (SELECT MIN(home_price) as min_home_price 
          FROM ourCommunity 
          INNER JOIN readyBuilt 
                 ON community = home_community 
          INNER JOIN rb_locations 
                 ON readyBuilt.home_location = rb_locations.locationId 
          WHERE id IN ( SELECT DISTINCT id 
                        FROM ourCommunity 
                        INNER JOIN readyBuilt 
                               ON community = home_community 
                        WHERE isDeleted = 0 
                               AND is_upcoming = 0) 
                 AND home_status = 1 
          GROUP BY id,name,community,mapLocation,locationLabel,logo 
          ORDER BY name) as org_min_home_price 
FROM ourCommunity 
INNER JOIN readyBuilt 
   ON community = home_community 
INNER JOIN rb_locations 
   ON readyBuilt.home_location = rb_locations.locationId 
WHERE id IN ( SELECT DISTINCT id 
                 FROM ourCommunity 
                 INNER JOIN readyBuilt 
                        ON community = home_community 
                 WHERE isDeleted = 0 AND is_upcoming = 0) 
   AND home_status = 1 
 GROUP BY id,name,community,mapLocation,locationLabel,logo 
 ORDER BY name

但是當我執行第二個查詢時，我收到此錯誤

子查詢返回多行

當我刪除GROUP BY ， MIN(home_price)沒有錯誤，每行都是相同的。 有沒有人對如何完成我想要完成的事情有任何建議？

Answer 1

通常情況下，如果您將price作為過濾器添加，則返回的最低價格將不是表格的實際最小值。

您可以加入由社區分組的每個min（home_price）的結果集

SELECT min_home_price,   
   id,
   name,
   community,
   maplocation,
   locationLabel,
   logo 
FROM ourCommunity
INNER JOIN (select min(home_price) min_home_price, home_community from readyBuilt group by home_community) b on b.home_community = community
INNER JOIN readyBuilt a ON community = a.home_community 
INNER JOIN rb_locations ON a.home_location = rb_locations.locationId 
WHERE id IN ( SELECT DISTINCT id 
                 FROM ourCommunity 
                 INNER JOIN readyBuilt ON community = home_community 
                 WHERE isDeleted = 0) 
AND home_status = 1 
GROUP BY id,name,community,mapLocation,locationLabel,logo 
ORDER BY name;

Answer 2

不要在MySQL中使用嵌套子查詢來處理大型數據集，否則MySQL最終可能會自己創建臨時表，並且查詢性能將受到影響。

我試圖刪除最后一個嵌套查詢，如下所示：

SELECT b.min_home_price,   
oc.id, oc.name, oc.community, oc.maplocation, oc.locationLabel, oc.logo
FROM ourCommunity oc
INNER JOIN (select min(home_price) min_home_price, home_community from readyBuilt group by home_community) b on b.home_community = oc.community
INNER JOIN readyBuilt rb ON oc.community = rb.home_community 
INNER JOIN rb_locations rbl ON rb.home_location = rbl.locationId 
INNER JOIN readyBuilt rb1 ON oc.community = rb1.home_community
WHERE rb1.isDeleted = 0
AND oc.home_status = 1 
 GROUP BY oc.id, oc.name, oc.community, oc.mapLocation, oc.locationLabel, oc.logo 
 ORDER BY oc.name;

如果你能請上傳您的3個表定義，並用簡單的英語總體目標，即WHAT是你想實現而不是開始HOW你開始解決這個問題，可能是我可以用更簡單的查詢幫助。

Answer 3

在第二個查詢中，當您沒有組時，只會獲得一行，因為您為整個表選擇了min（home_price）。

當您添加“分組依據”時，您將獲得每個ID，每個名稱，每個社區等的min（home_price）。

您需要更改子查詢以獲取外部查詢的當前行的min（home_price）。 可以將子查詢視為基於某些參數（恰好與外部查詢中的列匹配）返回值的函數。

我還懷疑你在子查詢中只需要一個表 - 一個有價格的表。 其他表可能會為您提供位置分組，因此它們屬於外部查詢。 （嘗試讓外部查詢在沒有最低價格和最后價格的情況下工作）。

例如

選擇id，name等...，（從p中選擇min（price）p.id = oc.id）作為我們社區oc inner join等的minPrice ... group by ...

正如其他答案所示，有很多方法可以實現這一點，例如連接而不是子查詢。 除非性能是一個問題，否則每個都有利弊，只需使用最容易理解和維護的內容。