Xor between two conditions in SQL Server

Question

There are OR and AND operators in T-SQL. AND means when two conditions are true and OR means if only first condition is true, if only second condition is true or if both conditions are true.

But I need something like XOR which is like OR but if both are true, the WHERE condition is not applied.

Example :

select * 
from [Table] 
where Id in (@FromId) XOR TypeId = @TypeId

My question is: how should I write this query so if Id in (@FromId) found, it doesn't check TypeId =@TypeId and if Id in (@FromId) isn't found, it checks for TypeId =@TypeId .

I know that I can write this for solving the problem :

select * from [Table] where Id in (@FromId) 
if @@ROWCOUNT =0
select * from  [Table] where TypeId =@TypeId

but I want write it in one query, for simplicity, performance, less code ,....

Thanks in advance.

Answer 1

Basically an XOR can be expressed in terms of AND and OR as follows:

 (cond1 AND NOT cond2) OR (NOT cond1 AND cond2)

So your query can be written as

select * 
from [Table] 
where (Id in (@FromId) AND TypeId <> @TypeId) OR (Id NOT IN (@FromId) AND TypeId = @TypeId)