我需要查询一些数据。这是我构建的查询,但对我来说这不是很好。对于此示例,我使用的是AdventureWorks数据库。
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。如何在同一THEN
的{{1}}中有多个where条件子句?我怎样才能做到这一点?
答案 0 :(得分:4)
这不是剪切和粘贴。 CASE
表达式必须返回一个值,并且您返回一个包含SQL的字符串(从技术上讲,它是一个值但类型错误的字符串)。这就是你想写的东西,我想:
SELECT * FROM [Purchasing].[Vendor] WHERE
CASE
WHEN @url IS null OR @url = '' OR @url = 'ALL'
THEN PurchasingWebServiceURL LIKE '%'
WHEN @url = 'blank'
THEN PurchasingWebServiceURL = ''
WHEN @url = 'fail'
THEN PurchasingWebServiceURL NOT LIKE '%treyresearch%'
ELSE PurchasingWebServiceURL = '%' + @url + '%'
END
我也怀疑这可能不适用于某些方言,但由于没有布尔值,现在无法测试(甲骨文,我在看你)。
但是,由于@url
不依赖于表值,为什么不进行三个不同的查询,并根据您的参数选择要评估的查询?
答案 1 :(得分:4)
基于amadan的另一种方式:
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