Conditional SQL Statement DB2 Based on columns

I'm not sure if this is possible, I have a java program which runs a given query (JDBC) and outputs the results into an excel file. The connection/db info is IBM as400, V7R1M0.

Let's say I have the following tables:

 ====================    =================================
 |      TABLE1      |    |             TABLE2            | 
 ====================    =================================   
 | Company |  CODE  |    |  ID   | CODE1 | CODE2 | CODE3 |
 --------------------    --------------------------------
 |   001   |   E1   |    |   1   |  10   |  18   |   21  |
 |   005   |   E3   |    |   2   |  14   |  19   |   23  |
 |   009   |   E1   |    |   3   |  17   |  20   |   25  |   
 |   015   |   E2   |    |   4   |   5   |  11   |   15  |
 ====================    =================================

My expected results will be like:

==============================
           RESULTS
==============================
|  Company  |  CODE  | CODE3 |
------------------------------
|    005    |   E3   |   21  |
==============================

Note(s):

TABLE1.CODE will tell us what column from TABLE2 to choose from.

TABLE1.COMPANY's CODE changes randomly

I only need one row from TABLE2, assume ID = 1 always.

I'm not sure how to approach this. I read that IBM AS400 doesn't allow IF ... ELSE.

My idea is kinda-of like (Pseudocode):

SET Value = SELECT CODE FROM TABLE1 WHERE Company ='005'
IF Value = 'E1'
   SELECT CODE1 FROM TABLE1 WHERE ID = 1;
ELSE IF Value = 'E2'
   SELECT CODE2 FROM TABLE1 WHERE ID = 1;
...

EDIT

I know I can do this in Java. but I don't want to change it. Can it be done from SQL statement?

Solution

You can express this as a SQL query:

select t1.company, t1.code,
       (case when t1.code = 'E1' then t2.code1
             when t1.code = 'E2' then t2.code2
             when t1.code = 'E3' then t2.code3
        end) as t1_code
from table1 t1 join
     table2 t2
     on t2.id = 1;