SQL>
SQL> -- change constant number
SQL>
SQL> declare
2 myconstant constant number := 50;
3 begin
4 myconstant := 51;
5 end;
6 /
myconstant := 51;
*
ERROR at line 4:
ORA-06550: line 4, column 5:
PLS-00363: expression 'MYCONSTANT' cannot be used as an assignment target
ORA-06550: line 4, column 5:
PL/SQL: Statement ignored
SQL>