Question

我有一个查询：

orp      CategoryId     Category        City      

999         1           bouquets        city-a       
999         2           arrengmnt       city-b       
999         4           chocolate       city-c

我想在每一行中添加具有以下类别的商店数量：

orp     CategoryId      Category        City      NoShops

999         1           bouquets        city-a       10
999         2           arrengmnt       city-b       14
999         4           chocolate       city-c       3

我需要获得CategoryId（@CategoryId），所以我在考虑这样的事情（显然不起作用）：

SELECT  Categories.OrderInPage as orp, CategoriesInLanguages.CategoryName,  @CategoryId = Categories.Id     
                ,(
                    SELECT COUNT(Shops.Id) as NoShops
                        FROM  Cities INNER JOIN
                                      CitiesInLanguages ON Cities.Id = CitiesInLanguages.CityId INNER JOIN
                                      ShopsInCities ON Cities.Id = ShopsInCities.CityId INNER JOIN
                                      CategoriesInLanguages INNER JOIN
                                      Categories ON CategoriesInLanguages.CategoryId = Categories.Id INNER JOIN
                                      ProductstInCategories ON Categories.Id = ProductstInCategories.CategoryId 
                        WHERE      (Products.IsEnable = 1)  AND ( Categories.Id = @CategoryId)) AS Z  
                )
        FROM  Cities INNER JOIN
                          CitiesInLanguages ON Cities.Id = CitiesInLanguages.CityId INNER JOIN
                          ShopsInCities ON Cities.Id = ShopsInCities.CityId INNER JOIN
                          CategoriesInLanguages INNER JOIN
                          Categories ON CategoriesInLanguages.CategoryId = Categories.Id INNER JOIN
                          ProductstInCategories ON Categories.Id = ProductstInCategories.CategoryId 
        WHERE      (Products.IsEnable = 1)

Answer 1

您无法混合这两项操作。如果您尝试它，错误消息是不言自明的。

为变量赋值的SELECT语句不能是结合数据检索操作。

Answer 2

在MySQL中，您可以执行以下操作： SELECT col1, col2, col3 FROM table1 WHERE col3 = param，但不能同时混合两个操作。我认为此规则适用于Sql Server。但是，现在很清楚你想要做什么。你能更具体一点吗？

Answer 3

你只能拥有

Select col1, col2, col3 from table1

或

Select  @param1 = col1, @param2 =  col2, @param3 = col3 from table1 where id=value

而不是两者。注意我添加了WHERE子句，您的查询应返回1行以使用@param

如果您使用了第二个选项，则可以执行以下操作

Select  @param1 as col1, @param2 as  col2, @param3 as col3

返回结果

从其中一个字段中获取价值

3 个答案: