Question

这是我的条件。

我有三个包含以下列的表

Recipe 
   - rID
   - pID
   - ingID
   - ingAmount

Product
   -pID
   -pName

Ingredient
   - ingID
   - ingName

对于Recpe Table，Recipe.ingID，Recipe.pID是从Product的Product.pID（主键）引用的，而相同的ingredient.ingID也是从Product.ingID引用的。

一般来说，

Recipe.pID = Product.pID
Recipe.ingID = Product.pID
Recipe.ingID = Ingredient.ingID

我想在ACCESS中使用单个查询来检索以下列。

我试过以下：

SELECT Recipe.pID, Product.pName, Recipe.ingID, 
       Ingredient.ingName, Recipe.ingAmount 
  FROM Recipe, Product, Ingredient 
 WHERE Recipe.pID = 5 
       AND (
            Recipe.ingID = Ingredient.ingID 
            OR Recipe.ingID = Product.pID
           );

问题是，首先评估(Recipe.ingID = Ingredient.ingID OR Recipe.ingID = Product.pID)部分，因此查询多行。

如果你有我想问的问题，请帮助我。

Answer 1

SELECT Recipe.pID, Recipe.ingID, Recipe.ingAmount, 
       Ingredient.ingName AS element_name, 
       'Ingredient' AS element_type
  FROM Recipe INNER JOIN Ingredient
          ON Recipe.ingID = Ingredient.ingID 
 WHERE Recipe.pID = 5 
UNION
SELECT Recipe.pID, Recipe.ingID, Recipe.ingAmount, 
       Product.pName AS element_name, 
       'Product' AS element_type
  FROM Recipe INNER JOIN Product
          ON Recipe.pID = Product.pID
 WHERE Recipe.pID = 5
UNION
SELECT Recipe.pID, Recipe.ingID, Recipe.ingAmount, 
       Product.pName AS element_name, 
       'Product as Ingredient' AS element_type
  FROM Recipe INNER JOIN Product
          ON Recipe.ingID = Product.pID
 WHERE Recipe.pID = 5;

如何在访问我的条件时查询多个数据库

1 个答案: