pl/sql 实例精解 08

   1:  EXCEPTION

   2:    WHEN EXCEPTION_NAME THEN

   3:      ERROR-PROCESSING STATEMENTS;

写在 begin 与 end 的之间的处理异常块.

常见异常: 20个.

多个异常

   1:  declare

   2:      v_student_id        NUMBER := &sv_student_id;

   3:      v_enrolled            VARCHAR2(3) := 'NO';

   4:  begin

   5:      DBMS_OUTPUT.PUT_LINE('Check if the student is enrolled');

   6:      SELECT 'yes'

   7:        INTO v_enrolled

   8:        from enrollment

   9:       where student_id = v_student_id;

  10:      

  11:      dbms_output.put_line('The student is enrolled into one course');

  12:  EXCEPTION

  13:      when no_data_found then

  14:          dbms_output.put_line('The student is not enrolled');

  15:      when too_many_rows then

  16:          dbms_output.put_line('The student is enrolled in too many courses');

  17:  end;

  18:  /

  19:  show errors;