Question

这个查询给了我错误，所以这个查询有什么问题？

SELECT recipes.recipeId as recipeId,
       recipes.title as title, 
       recipes.cookingtime as cookingtime, 
       recipes.serving as serving, 
       schedule.catId as catId, 
       images.imagePath AS imagePath 
  FROM recipes 
 INNER JOIN schedule ON recipes.recipeId = schedule.recipeId 
 INNER JOIN images   ON images.recipeId = recipes.recipeId 
 GROUP BY recipeId
 WHERE schedule.day = 'saturday'  
 ORDER BY catId ASC

我认为查询中group by的位置不正确。

Answer 1

应该是那样的，然后分组，然后命令

      WHERE schedule.day = 'saturday' 
     GROUP BY recipeId

    ORDER BY catId ASC

Answer 2

你的想法是正确的。 GROUP BY应该在WHERE子句之后和ORDER BY子句之前。

SELECT recipes.recipeId as recipeId,
       recipes.title as title, 
       recipes.cookingtime as cookingtime, 
       recipes.serving as serving, 
       schedule.catId as catId, 
       images.imagePath AS imagePath 
  FROM recipes 
 INNER JOIN schedule ON recipes.recipeId = schedule.recipeId 
 INNER JOIN images   ON images.recipeId = recipes.recipeId 
 WHERE schedule.day = 'saturday'  
 GROUP BY recipeId
 ORDER BY catId ASC

Answer 3

此处没有聚合功能，您无法使用group by。 group by条件在where子句之后和order by子句之前。

SELECT recipes.recipeId as recipeId,
           recipes.title as title, 
           recipes.cookingtime as cookingtime, 
           recipes.serving as serving, 
           schedule.catId as catId, 
           images.imagePath AS imagePath 

    FROM 
           recipes INNER JOIN schedule 
                              ON recipes.recipeId = schedule.recipeId 

                                        INNER JOIN images 
                                                   ON images.recipeId = recipes.recipeId 

 --   GROUP BY recipeId

    WHERE schedule.day = 'saturday'  ORDER BY catId ASC

Answer 4

只需替换

的顺序

GROUP BY recipeId

之后

WHERE schedule.day = 'saturday'

它需要......

SELECT recipes.recipeId as recipeId,
       recipes.title as title, 
       recipes.cookingtime as cookingtime, 
       recipes.serving as serving, 
       schedule.catId as catId, 
       images.imagePath AS imagePath 
 FROM recipes 
 INNER JOIN schedule ON recipes.recipeId = schedule.recipeId 
 INNER JOIN images   ON images.recipeId = recipes.recipeId 
 WHERE schedule.day = 'saturday'  
 GROUP BY recipeId
 ORDER BY catId ASC

这个SQL查询有什么问题

4 个答案: