Question

我尝试使用UNION ALL，但收到了错误：

您的SQL语法有错误;检查手册对应于您的MySQL服务器版本，以便使用正确的语法靠近'）GROUP BY Product_id'在第13行

如何为UNION表和结果GROUP BY设置正确的别名？

示例

Answer 1

这是正确的查询结构，UNION / ALL不需要别名，但Derived表会。

SELECT
  Product_id,
  sum(Total) as sumOfTotal
FROM ((SELECT
  b.Products_idProducts AS Product_id,
  COUNT(b.Products_idProducts) AS Total
FROM products_has_colors a
RIGHT JOIN products_has_colors b
  ON a.Colors_idColors = b.Colors_idColors
  AND b.Products_idProducts <> a.Products_idProducts
WHERE a.Products_idProducts = 1
GROUP BY b.Products_idProducts)

UNION ALL

(SELECT
  b.Products_idProducts AS Product_id,
  COUNT(b.Products_idProducts) AS Total
FROM Products_has_ProductComposition a
RIGHT JOIN Products_has_ProductComposition b
  ON (a.CompositionId = b.CompositionId
  AND b.Products_idProducts <> a.Products_idProducts)
WHERE a.Products_idProducts = 1
GROUP BY b.Products_idProducts)) mytable
GROUP BY Product_id;

Answer 2

你的别名是错误的，你有一些你不需要的括号。您需要为整个UNION查询设置别名，如下所示：

SELECT product_ID
FROM (
  SELECT BLAH
  UNION
  SELECT BLAH2
     ) as t1
GROUP BY product_ID;

在你的情况下应该是这样的：

SELECT Product_id 
FROM (
  SELECT b.Products_idProducts AS Product_id, COUNT(b.Products_idProducts) AS Total 
  FROM products_has_colors a
  RIGHT JOIN products_has_colors b 
  ON a.Colors_idColors = b.Colors_idColors AND b.Products_idProducts <> a.Products_idProducts
  WHERE a.Products_idProducts = 1 
  GROUP BY b.Products_idProducts

  UNION ALL

  SELECT b.Products_idProducts AS Product_id, COUNT(b.Products_idProducts) AS Total 
  FROM Products_has_ProductComposition a
  RIGHT JOIN Products_has_ProductComposition b 
  ON (a.CompositionId = b.CompositionId AND b.Products_idProducts <> a.Products_idProducts)
  WHERE a.Products_idProducts = 1 
  GROUP BY b.Products_idProducts
      ) as t1
GROUP BY Product_id;

Answer 3

表名别名（t1）的错误positioon

SELECT Product_id FROM (

  (SELECT
       b.Products_idProducts AS Product_id
       , COUNT(b.Products_idProducts) AS Total 
       FROM products_has_colors a
       RIGHT JOIN products_has_colors b  ON a.Colors_idColors = b.Colors_idColors 
          AND b.Products_idProducts <> a.Products_idProducts
      WHERE a.Products_idProducts = 1 
      GROUP BY b.Products_idProducts) 

UNION ALL

  (SELECT 
        b.Products_idProducts AS Product_id
        , COUNT(b.Products_idProducts) AS Total 
        FROM Products_has_ProductComposition a
        RIGHT JOIN Products_has_ProductComposition b ON a.CompositionId = b.CompositionId 
          AND b.Products_idProducts <> a.Products_idProducts
          WHERE a.Products_idProducts = 1 GROUP BY b.Products_idProducts) 
        GROUP BY Product_id)  t1

我在查询SQL（UNION ALL）中错误的地方？

3 个答案: