Conditional Inner Join

Question

I want to be able to inner join two tables based on the result of an expression.

What I\'ve been trying so far:

INNER JOIN CASE WHEN Reg         


        

Answer 1

You probably need to perform two left joins, one onto TimeRegistration and one onto DrivingRegistration, and return the fields you want from the appropriate join table something like this:

LEFT JOIN TimeRegistration ON TimeRegistration.RegistreringsId = R.Id
LEFT JOIN DrivingRegistration ON DrivingRegistration.RegistreringsId = R.Id

and you select statement would be something like this:

SELECT CASE WHEN RegT.Type = 1 THEN TimeRegistration.Foo ELSE DrivingRegistration.Bar END

I like what you're trying to do, but I don't think SQL is that clever.