基于案例查询的不同连接/更新答案

【问题标题】：Different join/update based on case query基于案例查询的不同连接/更新
【发布时间】：2015-06-17 18:20:12
【问题描述】：

我正在尝试使用以下代码来运行基于 CASE 语句的不同 join 查询。

所以如果customer CLI 等于84422881 我希望它基于[Extenstion] 字段加入，如果不满足条件即ELSE 然后加入[Customer CLI]

use VoiceflexBilling

CASE WHEN [dbo].[MARU15_OWH07579_Calls].[CustomerCLI] = '84422881' THEN

UPDATE [dbo].[MARU15_OWH07579_Calls] 
SET [dbo].[MARU15_OWH07579_Calls].[CustomerLookup] = CLIMapping.[customer id] 
FROM [BillingReferenceData].[dbo].[CLIMapping] 
INNER JOIN [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls] 
on [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls].[Extension] = [BillingReferenceData].[dbo].[CLIMapping].[CLI]

ELSE

UPDATE [dbo].[MARU15_OWH07579_Calls] 
SET [dbo].[MARU15_OWH07579_Calls].[CustomerLookup] = CLIMapping.[customer id] 
FROM [BillingReferenceData].[dbo].[CLIMapping] 
INNER JOIN [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls] 
on [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls].[CustomerCLI] = [BillingReferenceData].[dbo].[CLIMapping].[CLI]

END

目前我收到以下错误：

Msg 156, Level 15, State 1, Line 3 关键字附近的语法错误 '案子'。消息 156，级别 15，状态 1，第 11 行关键字“其他”。消息 102，级别 15，状态 1，第 19 行语法不正确 'END'附近。

任何人都可以帮助使用正确的语法吗？

谢谢，

【问题讨论】：

标签： sql sql-server join sql-update case

【解决方案1】：

您的查询中有一些 cmets。首先，case 是一个表达式，而不是控制流。所以，它属于一个查询。其次，您可以对此查询使用“常规”逻辑。第三，表别名将使查询更易于编写和阅读：

UPDATE c 
SET c.[CustomerLookup] = CLIMapping.[customer id] 
FROM [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls] cm
     [BillingReferenceData].[dbo].[CLIMapping] c INNER JOIN
     on (c.[CustomerCLI] = '84422881' AND c.[Extension] = cm.[CLI]) or
        (c.[CustomerCLI] <> '84422881' AND c.[CustomerCLI] = cm.[CLI])

【讨论】：

【解决方案2】：

您可以在join condition 中使用case 语句：

UPDATE [dbo].[MARU15_OWH07579_Calls] 
SET [dbo].[MARU15_OWH07579_Calls].[CustomerLookup] = CLIMapping.[customer id] 
FROM [BillingReferenceData].[dbo].[CLIMapping] 
INNER JOIN [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls] 
ON [BillingReferenceData].[dbo].[CLIMapping].[CLI] = 
 CASE WHEN [dbo].[MARU15_OWH07579_Calls].[CustomerCLI] = '84422881' 
                 THEN [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls].[Extension]
      ELSE [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls].[CustomerCLI] 
 END

【讨论】：

【解决方案3】：

案例必须出现在查询中。对于您的场景，我建议您编写代码如下：（您需要实现循环以遍历所有记录，在这种情况下，您需要稍微修改此代码)

DECLARE @p varchar(100)
SET @p=(SELECT TOP 1 [dbo].[MARU15_OWH07579_Calls].[CustomerCLI] FROM [dbo].[MARU15_OWH07579_Calls])
IF @p = '84422881'
   UPDATE [dbo].[MARU15_OWH07579_Calls] 
   SET [dbo].[MARU15_OWH07579_Calls].[CustomerLookup] = CLIMapping.[customer id] 
   FROM [BillingReferenceData].[dbo].[CLIMapping] 
   INNER JOIN [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls] 
   on [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls].[Extension] =[BillingReferenceData].[dbo].[CLIMapping].[CLI]

ELSE
   UPDATE [dbo].[MARU15_OWH07579_Calls] 
   SET [dbo].[MARU15_OWH07579_Calls].[CustomerLookup] = CLIMapping.[customer id] 
   FROM [BillingReferenceData].[dbo].[CLIMapping] 
   INNER JOIN [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls] 
   on [VoiceflexBilling].[dbo].[MARU15_OWH07579_Calls].[CustomerCLI] = [BillingReferenceData].[dbo].[CLIMapping].[CLI]

【讨论】：