Is it possible in from clause use case when statement

Question

I am trying to do next query:

select * from (case when :p1 = '1' then t1 when :p1=2 then t2);

But it's not working. I assume that case when statement isn't allowed in from clause? Is there any other any way to resolve this. Thanks

Answer 1

No, you can't do that. The objects and identifiers have to be fixed when the query is parsed, so you can't bind those.

You could use a union with a check for the variable in each branch:

select * from t1
where :p1 = 1
union all 
select * from t2
where :p1 = 2;

assuming the structure of the tables is the same.