As table name is not known at compile time you need to use dynamic SQL(execute immediate, native dynamic SQL, for instance) to be able to select from a table, name of which is stored as a string literal - you cannot accomplish it with static SQL
Here is an example:
-- table which contains names of other tables
-- in the table_name column
SQL> create table Table_Names as
2 select 'employees' as table_name
3 from dual
4 ;
Table created
SQL> set serveroutput on;
-- example of an anonymous PL/SQL block
-- where native dynamic SQL (execute immediate statement)
-- is used to execute a dynamically formed select statement
SQL> declare
2 type T_record is record( -- example of record for fetched data
3 f_name varchar2(123),
4 l_name varchar2(123)
5 );
6
7 l_table_name varchar2(123); -- variable that will contain table name
8 l_select varchar2(201);
9 l_record T_Record; -- record we are going to fetch data into
10 begin
11 select table_name
12 into l_table_name -- querying a name of a table
13 from table_names -- and storing it in the l_table_name variable
14 where rownum = 1;
15
16 l_select := 'select first_name, last_name from ' ||
17 dbms_assert.simple_sql_name(l_table_name) ||
18 ' where rownum = 1'; -- forming a query
19
20 execute immediate l_select -- executing the query
21 into l_record;
22 -- simple output of data just for the sake of demonstration
23 dbms_output.put_line('First_name: ' || l_record.f_name || chr(10) ||
24 'Last name: ' || l_record.l_name);
25 exception
26 when no_data_found
27 then dbms_output.put_line('Nothing is found');
28 end;
29 /
First_name: Steven
Last name: King
PL/SQL procedure successfully completed
As a second option you could use weakly typed cursors - refcursors to execute a dynamically formed select statement:
SQL> variable refcur refcursor;
SQL> declare
2 l_table_name varchar2(123);
3 l_select varchar2(201);
4 begin
5 select table_name
6 into l_table_name
7 from table_names
8 where rownum = 1;
9
10 l_select := 'select first_name, last_name from ' ||
11 dbms_assert.simple_sql_name(l_table_name) ||
12 ' where rownum = 1';
13
14 open :refcur
15 for l_select;
16
17 exception
18 when no_data_found
19 then dbms_output.put_line('Nothing is found');
20 end;
21 /
PL/SQL procedure successfully completed.
SQL> print refcur;
FIRST_NAME LAST_NAME
-------------------- -------------------------
Steven King
SQL> spool off;
Find out more about cursors and cursor variables