SQL> create table tab_200401 (empno number, payperiod number, grossal number);

Table created.

SQL> insert into tab_200401 values (1234, 200401, 10000);

1 row created.

SQL> create table tab_200402 as select * From tab_200401;

Table created.

SQL> update tab_200402 set payperiod = 200402;

1 row updated.

SQL> create view salaries as
  2  select empno, payperiod, grossal from tab_200401
  3  union
  4  select empno, payperiod, grossal from tab_200402;

View created.

SQL> select 'tab_' || payperiod, empno, grossal
  2  from salaries
  3  where empno = 1234
  4    and payperiod <= 200402;

'TAB_'||PAYPERIOD                                 EMPNO    GROSSAL
-------------------------------------------- ---------- ----------
tab_200401                                         1234      10000
tab_200402                                         1234      10000

SQL>