使用CASE语句的多个条件 [英] Multiple conditions with CASE statements

问题描述

我需要查询一些数据.这是我构造的查询，但对我来说不起作用.对于此示例，我正在使用AdventureWorks数据库.

I need to query some data. here is the query that i have constructed but which isn't workig fine for me. For this example I am using AdventureWorks database.

SELECT * FROM [Purchasing].[Vendor] WHERE PurchasingWebServiceURL LIKE 
case
// In this case I need all rows to be returned if @url is '' or 'ALL' or NULL
 when (@url IS null OR @url = '' OR @url = 'ALL') then ('''%'' AND PurchasingWebServiceURL IS NULL')
//I need all records which are blank here including nulls
         when (@url = 'blank') then (''''' AND PurchasingWebServiceURL IS NULL' )
//n this condition I need all record which are not like a particular value
         when (@url = 'fail') then ('''%'' AND PurchasingWebServiceURL NOT LIKE ''%treyresearch%''' )
//Else Match the records which are `LIKE` the input value
         else '%' + @url + '%' 
    end

这对我不起作用.在同一个 CASE 的 THEN 中，如何有多个where条件子句?我该如何进行这项工作?

This is not working for me. How can I have multiple where condition clauses in the THEN of the the same CASE? How can I make this work?

推荐答案

基于amadan的另一种方法:

Another way based on amadan:

    SELECT * FROM [Purchasing].[Vendor] WHERE  

      ( (@url IS null OR @url = '' OR @url = 'ALL') and   PurchasingWebServiceURL LIKE '%')
    or

       ( @url = 'blank' and  PurchasingWebServiceURL = '')
    or
        (@url = 'fail' and  PurchasingWebServiceURL NOT LIKE '%treyresearch%')
    or( (@url not in ('fail','blank','','ALL') and @url is not null and 
          PurchasingWebServiceUrl Like '%'+@ur+'%') 
END

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