Optimize view that dynamically choose a table or another - sql

Question

So the problem is that I have three huge table with same structure, and I need to show the results of one of them depending on result from another query.
So my order table looks like that:
code order
A 0
B 2
C 1
And I need to retrieve data from t_results
My approach (which is working) looks like this:
select *
from t_results_a
where 'A' in (
select code
from t_order
where order = 0
)
UNION ALL
select *
from t_results_b
where 'B' in (
select code
from t_order
where order = 0
)
UNION ALL
select *
from t_results_c
where 'C' in (
select code
from t_order
where order = 0
)
Is there anyway to not scan all three tables, as I am working with Athena so I can't program?

Answer 1

I presume that changing your database schema is not an option.
If it were, you could use one database table and add a CODE column whose value would be either A, B or C.
Basically the result of the SQL query on your ORDER table determines which other database table you need to query. For example, if CODE in table ORDER is A, then you have to query table T_RESULTS_A.
You wrote in your question
I am working with Athena so I can't program
I see that there is both an ODBC driver and a JDBC driver for Athena, so you can program with either .NET or Java. So you could write code that queries the ORDER table and use the result of that query to build another query string to query just the relevant table.
Another thought I had was dynamic SQL. Oracle database supports it. I can create a string containing variables where one variable is the database table name and have Oracle interpret the string as SQL and execute it. I briefly searched the Internet to see whether Athena supports this (as I have no experience with Athena) but found nothing - which doesn't mean to say that it does not exist.