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
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?
It's not a cut and paste. The CASE
expression must return a value, and you are returning a string containing SQL (which is technically a value but of a wrong type). This is what you wanted to write, I think:
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
I also suspect that this might not work in some dialects, but can't test now (Oracle, I'm looking at you), due to not having booleans.
However, since @url
is not dependent on the table values, why not make three different queries, and choose which to evaluate based on your parameter?
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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