pl/sql 实例精解 08

EXCEPTION
  WHEN EXCEPTION_NAME THEN
    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

declare
    v_student_id        NUMBER := &sv_student_id;
    v_enrolled            VARCHAR2(3) := 'NO';
begin
    DBMS_OUTPUT.PUT_LINE('Check if the student is enrolled');
    SELECT 'yes'
      INTO v_enrolled
      from enrollment
     where student_id = v_student_id;

    dbms_output.put_line('The student is enrolled into one course');
EXCEPTION
    when no_data_found then
        dbms_output.put_line('The student is not enrolled');
    when too_many_rows then
        dbms_output.put_line('The student is enrolled in too many courses');
end;
/
show errors;