Select from different tables depending on results

Question

how to do this in one select
4 tables
t3 and t4 are identical in structure but different data
select id from t1
If exists in select id from t2
then select data from t3
else
select data from t4
create table t1 (id number);
create table t2 (id number);
create table t3 (col1 varchar2(10), col2 varchar2(10));
create table t4 (col1 varchar2(10), col2 varchar2(10));
insert into t1 values(1);
insert into t1 values(2);
insert into t2 values(1);
insert into t3 values('DATA1','DATA2');
insert into t4 values('DATA3','DATA4');
commit;
Ive put values 1 and 2 into t1. as id=1 exists in t2, for that record I want the values from t3 but where id=2, I want the values from t4.
Possible in one select?   Ive been playing with case statement but not getting anywhere near it

Answer 1

Having multiple table with same structure looks like a design flaw. What benefit that does bring. So please explain the reason to have 2 table with same structure.
Said that here are few more ways.
SQL> select id
  2       , col1
  3       , col2
  4    from (
  5            select t1.id
  6                 , decode(t2.id, null, 'T4', 'T3') table_handle
  7              from t1
  8              left
  9              join t2
10                on t1.id = t2.id
11         ) a
12    join (
13            select 'T3' table_handle, col1, col2 from t3
14            union all
15            select 'T4' table_handle, col1, col2 from t4
16         ) b
17      on a.table_handle = b.table_handle;
        ID COL1       COL2
         1 DATA1      DATA2
         2 DATA3      DATA4
SQL> select id
  2       , col1
  3       , col2
  4    from (
  5            select t1.id
  6                 , dbms_xmlgen.getxmltype('select col1, col2 from ' || decode(t2.id, null, 'T4', 'T3')) xml_data
  7              from t1
  8              left
  9              join t2
10                on t1.id = t2.id
11         )
12       , xmltable
13         (
14            '/ROWSET/ROW' passing xml_data
15            columns col1 varchar2(10) path 'COL1',
16                    col2 varchar2(10) path 'COL2'
17         );
        ID COL1       COL2
         1 DATA1      DATA2
         2 DATA3      DATA4
SQL>