Accessing package CONSTANT in a SQL query

Question

Hi,
Can anybody explain why I cannot access the package constant in a SQL but can use it in dbms_output.put_line:
SQL> create package scott.xx_test_const_pkg
2 as
3 a constant varchar2(1) :='A';
4 end;
5 /
Package created.
SQL> begin
2 dbms_output.put_line( scott.xx_test_const_pkg.a);
3 end;
4 /
A <------------------THIS WORKS
PL/SQL procedure successfully completed.
SQL> select * from scott.emp where ename=scott.xx_test_const_pkg.a;
select * from scott.emp where ename=scott.xx_test_const_pkg.a <------------------THIS DOES NOT WORK
ERROR at line 1:
ORA-06553: PLS-221: 'A' is not a procedure or is undefined
Thanks

Answer 1

You can't refer to a pl/sql package constant in a sql statement.
Create a function that returns the constant value and then refer to the function in a sql statement.