SQL multiple case statement - sql

Question

How can I make this correct? I am getting an error saying:
Incorrect syntax near the keyword 'DESC'.
SELECT *
FROM Companies
Order By
CASE #OrderByField
WHEN 'CompanyName' THEN CompanyName
WHEN 'CreatedDate' THEN CreatedDate
END,
CASE #Direction
WHEN 'DESC' THEN DESC
WHEN 'ASC' THEN ASC
END
Can I not have two case statements? If not, how can i pass in the name of the order by field and direction as parameters?
Thanks!
Another problem surface after the first one is solved...
If I include a field that doesn't have the datatype of string, if throws an error.
For example:
SELECT *
FROM Companies
Order By
CASE #Direction WHEN 'DESC' THEN
CASE #OrderByField
WHEN 'CompanyName' THEN CompanyName
WHEN 'CreatedDate' THEN CreatedDate
WHEN 'Score' THEN Score
END
END DESC,
CASE #Direction WHEN 'ASC' THEN
CASE #OrderByField
WHEN 'CompanyName' THEN CompanyName
WHEN 'CreatedDate' THEN CreatedDate
WHEN 'Score' THEN Score
END
END ASC
#OrderByField is type of nvarchar(50)
assume Score has a datatype of float.
Above throws an error like the one below even if i am not trying to order by the score field. Error converting data type nvarchar to float.
Similarly, including a createddate throws an error: Conversion failed when converting date and/or time from character string.
Will be very appreciated if anyone can help out.

Answer 1

You can't return a keyword from a case statement.
But you can achieve what you want by ordering in two ways, but return a constant expression for the order you don't want:
SELECT *
FROM Companies
Order By
CASE #Direction WHEN 'DESC' THEN
CASE #OrderByField
WHEN 'CompanyName' THEN CompanyName
WHEN 'CreatedDate' THEN CreatedDate
END
END DESC,
CASE #Direction WHEN 'ASC' THEN
CASE #OrderByField
WHEN 'CompanyName' THEN CompanyName
WHEN 'CreatedDate' THEN CreatedDate
END
END ASC
Non-matching cases will return null and so will be ignored for ordering purposes.

Answer 2

As ASC and DESC are keywords, you can't have them as return value from a CASE.
You can make two cases, one for ASC and one for DESC:
SELECT *
FROM Companies
Order By
CASE
WHEN #OrderByField = 'CompanyName' AND #Direction = 'ASC' THEN CompanyName
WHEN #OrderByField = 'CreatedDate' AND #Direction = 'ASC' THEN CreatedDate
END ASC,
CASE
WHEN #OrderByField = 'CompanyName' AND #Direction = 'DESC' THEN CompanyName
WHEN #OrderByField = 'CreatedDate' AND #Direction = 'DESC' THEN CreatedDate
END DESC
Note that all values from a case has to have the same data type, so you might need one pair of cases for string and one pair for dates.