PL/SQL Exception - a simple test

Continue the effort to learn PL/SQL - This is about EXCEPTION, simple test.

denis@TEST10G> @exception_1
denis@TEST10G> rem This is the test case to test the following situation:
denis@TEST10G> rem
denis@TEST10G> rem 1. Not using any exception, which would result in an ORA-01403 error
denis@TEST10G> rem 2. Uisng predefined Oracle Database exception NO_DATA_FOUND
denis@TEST10G> rem 3. Using  user-defined exception
denis@TEST10G> rem
denis@TEST10G> 
denis@TEST10G> 
denis@TEST10G> drop table t;

Table dropped.

denis@TEST10G> 
denis@TEST10G> create table t
  2  as
  3  select
  4     rownum  empno,
  5     a.object_name ename
  6   from all_objects a
  7  where  rownum < 5000;

Table created.

denis@TEST10G> 
denis@TEST10G> 
denis@TEST10G> -- Case 1: exception not defined
denis@TEST10G> 
denis@TEST10G> declare
  2   emp_number integer :=5000;
  3   emp_name varchar2(50);
  4  begin
  5   select ename into emp_name from t
  6     where empno = emp_number;  -- no such number
  7   dbms_output.put_line('Employee name is ' || emp_name);
  8  end;
  9  /
declare
*
ERROR at line 1:
ORA-01403: no data found
ORA-06512: at line 5


denis@TEST10G> 
denis@TEST10G> 
denis@TEST10G> -- Case 2: using predefind Oracle exception
denis@TEST10G> 
denis@TEST10G> declare
  2   emp_number integer :=5000;
  3   emp_name varchar2(50);
  4  begin
  5   select ename into emp_name from t
  6     where empno = emp_number;  -- no such number
  7   dbms_output.put_line('Employee name is ' || emp_name);
  8  exception
  9   when no_data_found then
 10      dbms_output.put_line('No such employee:' || emp_number);
 11  end;
 12  /
No such employee:5000

PL/SQL procedure successfully completed.

denis@TEST10G> 
denis@TEST10G> 
denis@TEST10G> -- Case 3: using user-defined exception
denis@TEST10G> --  declare it in the delcaration part of a block
denis@TEST10G> --  define it in the exception part of the block
denis@TEST10G> 
denis@TEST10G> declare
  2   emp_number integer;
  3   emp_name varchar2(50);
  4   empno_out_of_range exception;
  5  begin
  6   emp_number := 5000;
  7   if emp_number > 4999 or emp_number < 1 then
  8      raise empno_out_of_range;
  9   else
 10      select ename into emp_name from t
 11        where empno = emp_number;
 12      dbms_output.put_line('Employee name is ' || emp_name);
 13   end if;
 14  exception
 15   when empno_out_of_range then
 16      dbms_output.put_line('Employee number:' || emp_number ||
 17       ' is out of range.');
 18  end;
 19  /
Employee number:5000 is out of range.

PL/SQL procedure successfully completed.