将具有多个条件的查询组合在一起时遇到问题答案

【问题标题】：Trouble putting together a query with multiple conditions将具有多个条件的查询组合在一起时遇到问题
【发布时间】：2019-04-10 00:06:26
【问题描述】：

我有一个查询库存水平。我需要根据软件中提供的 CustomerID 变量过滤项目。项目和客户之间没有直接连接。但是，我在客户中有自定义字段，它定义了允许他们从哪些项目组购买（布尔值）。我在 Item 中还有一个自定义字段，用于确定它属于哪个组（字符串）。

我尝试使用交叉连接，但正如您所想象的那样，我在右侧得到了空白项目和数据，这是我不想要的。我没有其余的（库存检查）查询，此时我正在尝试根据组获取要为客户显示的项目。我已将实际字段替换为 Group1、Group2 等。请忽略括号。

SELECT Customers.CustomerNo,
       Customers.CustomerID,
       Customers.Name,
       CASE
           WHEN Customers.[Group1] = 1
                AND Items.UserDefined1 = 'Group1'
           THEN Items.ItemNo
           WHEN Customers.Group2 = 1
                AND Items.UserDefined1 = 'Group2'
           THEN Items.ItemNo
           WHEN Customers.[Group3] = 1
                AND Items.UserDefined1 = 'Group3'
           THEN Items.ItemNo
           WHEN Customers.[Group4] = 1
                AND Items.UserDefined1 = 'Group4'
           THEN Items.ItemNo
           WHEN Customers.Group5 = 1
                AND Items.UserDefined1 = 'Group5'
           THEN Items.ItemNo
           WHEN Customers.[Group6] = 1
                AND Items.UserDefined1 = 'Group6'
           THEN Items.ItemNo
           WHEN Customers.[Group7] = 1
                AND Items.UserDefined1 = 'Group7'
           THEN Items.ItemNo
           WHEN Customers.[Group8] = 1
                AND Items.UserDefined1 = 'Group8'
           THEN Items.ItemNo
           WHEN Customers.[Group9] = 1
                AND Items.UserDefined1 = 'Group9'
           THEN Items.ItemNo
           WHEN Customers.Group10 = 1
                AND Items.UserDefined1 = 'Group10'
           THEN Items.ItemNo
           WHEN Customers.Group11 = 1
                AND Items.UserDefined1 = 'Group11'
           THEN Items.ItemNo
           ELSE ''
       END AS ItemNo,
       Items.Name AS Description,
       Items.UserDefined1
FROM
(
    SELECT Items_1.ItemNo,
           Items_1.Name,
           ItemsUserDefined.UserDefined1
    FROM dbo.Items AS Items_1
         INNER JOIN
(
    SELECT UserDefined1,
           OwnerID
    FROM dbo.AdditionalInfo
    WHERE(ModuleID = 12)
) AS ItemsUserDefined ON Items_1.ItemID = ItemsUserDefined.OwnerID
) AS Items
CROSS JOIN
(
    SELECT Customers_1.CustomerNo,
           Customers_1.Name,
           Customers_1.CustomerID,
           CustomerUserDefined.[Group1],
           CustomerUserDefined.Group2,
           CustomerUserDefined.[Group3],
           CustomerUserDefined.[Group4],
           CustomerUserDefined.Group5,
           CustomerUserDefined.[Group6],
           CustomerUserDefined.[Group7],
           CustomerUserDefined.[Group8],
           CustomerUserDefined.[Group9],
           CustomerUserDefined.Group10,
           CustomerUserDefined.Group11
    FROM dbo.Customers AS Customers_1
         INNER JOIN
(
    SELECT UserDefined9 AS [Group1],
           UserDefined10 AS Group2,
           UserDefined11 AS [Group3],
           UserDefined12 AS [Group4],
           UserDefined13 AS Group5,
           UserDefined14 AS [Group6],
           UserDefined15 AS [Group7],
           UserDefined16 AS [Group8],
           UserDefined17 AS [Group9],
           UserDefined18 AS Group10,
           UserDefined20 AS Group11,
           OwnerID
    FROM dbo.AdditionalInfo AS AdditionalInfo_1
    WHERE(ModuleID = 38)
) AS CustomerUserDefined ON Customers_1.CustomerID = CustomerUserDefined.OwnerID
) AS Customers
WHERE CustomerID = 472

【问题讨论】：

标签： tsql

【解决方案1】：

我使用 case 语句加入了 customer 和 items 表，因为这两个表之间没有直接链接。

查询

select items.name,customers.customerID, items.userdefined1
from customers
inner join Items on items.userdefined1 = (case when customers.group1 =1 then 'group1' 
                                               when customers.group2 =1 then 'group2' 
                                               when customers.group3 =1 then 'group3' 
                                               when customers.group4 =1 then 'group4' 
                                               when customers.group5 =1 then 'group5' 
                                          end )

输出

【讨论】：

我花了一分钟才弄清楚该放在哪里，但我想通了。谢谢！
好吧，case语句不正确，找到第一个匹配后停止解析。
你能分享你的查询吗？
查看修改后的查询

【解决方案2】：

因此，当 SQL 找到表达式的第一个 'TRUE' 时，它将停止解析。我需要它来返回所有真实的。

SELECT CustomerNo,
       CustomerID,
       Items.ItemNo,
       Items.Name AS Description
FROM
(
    SELECT Customers_1.CustomerNo,
           Customers_1.Name,
           Customers_1.CustomerID,
           CustomerUserDefined.[Group1],
           CustomerUserDefined.Group2,
           CustomerUserDefined.[Group3],
           CustomerUserDefined.[Group4],
           CustomerUserDefined.Group5,
           CustomerUserDefined.[Group6],
           CustomerUserDefined.[Group7],
           CustomerUserDefined.[Group8],
           CustomerUserDefined.[Group9],
           CustomerUserDefined.Group10,
           CustomerUserDefined.Group11
    FROM dbo.Customers AS Customers_1
         INNER JOIN
(
    SELECT UserDefined9 AS [Group1],
           UserDefined10 AS Group2,
           UserDefined11 AS [Group3],
           UserDefined12 AS [Group4],
           UserDefined13 AS Group5,
           UserDefined14 AS [Group6],
           UserDefined15 AS [Group7],
           UserDefined16 AS [Group8],
           UserDefined17 AS [Group9],
           UserDefined18 AS Group10,
           UserDefined20 AS Group11,
           OwnerID
    FROM dbo.AdditionalInfo AS AdditionalInfo_1
    WHERE(ModuleID = 38)
) AS CustomerUserDefined ON Customers_1.CustomerID = CustomerUserDefined.OwnerID
) AS Customers
INNER JOIN
(
    SELECT Items_1.ItemNo,
           Items_1.Name,
           ItemsUserDefined.UserDefined1
    FROM dbo.Items AS Items_1
         INNER JOIN
(
    SELECT UserDefined1,
           OwnerID
    FROM dbo.AdditionalInfo
    WHERE(ModuleID = 12)
) AS ItemsUserDefined ON Items_1.ItemID = ItemsUserDefined.OwnerID
) AS Items ON Items.UserDefined1 = (CASE
                                        WHEN Customers.[Group1] = 1
                                        THEN 'Group1'
                                        WHEN Customers.Group2 = 1
                                        THEN 'Group2'
                                        WHEN Customers.[Group3] = 1
                                        THEN 'Group3'
                                        WHEN Customers.[Group4] = 1
                                        THEN 'Group4'
                                        WHEN Customers.Group5 = 1
                                        THEN 'Group5'
                                        WHEN Customers.[Group6] = 1
                                        THEN 'Group6'
                                        WHEN Customers.[Group7] = 1
                                        THEN 'Group7'
                                        WHEN Customers.[Group8] = 1
                                        THEN 'Group8'
                                        WHEN Customers.[Group9] = 1
                                        THEN 'Group9'
                                        WHEN Customers.Group10 = 1
                                        THEN 'Group10'
                                        WHEN Customers.Group11 = 1
                                        THEN 'Group11'
                                    END)
WHERE CustomerID = 578;

【讨论】：

【解决方案3】：

在下面的示例中，客户 124 有两个组 3 的真实记录。 Case 语句返回两条记录。

    select items.name,customers.customerID, items.userdefined1
from customers
inner join Items on items.userdefined1 = (case when customers.group1 =1 then 'group1' 
                                               when customers.group2 =1 then 'group2' 
                                               when customers.group3 =1 then 'group3' 
                                               when customers.group4 =1 then 'group4' 
                                               when customers.group5 =1 then 'group5' 
                                          end )

我已修改以下查询。我没有直接使用 case 语句，而是将其用作子查询来获取 Items.UserDefined1。无法运行查询，因为我没有表 AdditionalInfo。

试试这个，

SELECT CustomerNo,
       CustomerID,
       Items.ItemNo,
       Items.Name AS Description
FROM
(
    SELECT Customers_1.CustomerNo,
           Customers_1.Name,
           Customers_1.CustomerID,
           CustomerUserDefined.[Group1],
           CustomerUserDefined.Group2,
           CustomerUserDefined.[Group3],
           CustomerUserDefined.[Group4],
           CustomerUserDefined.Group5,
           CustomerUserDefined.[Group6],
           CustomerUserDefined.[Group7],
           CustomerUserDefined.[Group8],
           CustomerUserDefined.[Group9],
           CustomerUserDefined.Group10,
           CustomerUserDefined.Group11
    FROM dbo.Customers AS Customers_1
         INNER JOIN
(
    SELECT UserDefined9 AS [Group1],
           UserDefined10 AS Group2,
           UserDefined11 AS [Group3],
           UserDefined12 AS [Group4],
           UserDefined13 AS Group5,
           UserDefined14 AS [Group6],
           UserDefined15 AS [Group7],
           UserDefined16 AS [Group8],
           UserDefined17 AS [Group9],
           UserDefined18 AS Group10,
           UserDefined20 AS Group11,
           OwnerID
    FROM dbo.AdditionalInfo AS AdditionalInfo_1
    WHERE(ModuleID = 38)
) AS CustomerUserDefined ON Customers_1.CustomerID = CustomerUserDefined.OwnerID
) AS Customers
INNER JOIN
(
    SELECT Items_1.ItemNo,
           Items_1.Name,
           ItemsUserDefined.UserDefined1
    FROM dbo.Items AS Items_1
         INNER JOIN
(
    SELECT UserDefined1,
           OwnerID
    FROM dbo.AdditionalInfo
    WHERE(ModuleID = 12)
) AS ItemsUserDefined ON Items_1.ItemID = ItemsUserDefined.OwnerID
) AS Items ON Items.UserDefined1 in(select items.userdefined1
                                    from customers
                                    inner join Items on items.userdefined1 = (case when customers.group1 =1 then 'group1' 
                                                                                   when customers.group2 =1 then 'group2' 
                                                                                   when customers.group3 =1 then 'group3' 
                                                                                   when customers.group4 =1 then 'group4' 
                                                                                   when customers.group5 =1 then 'group5' 
                                                                             end ))
WHERE CustomerID = 578;

【讨论】：