/*

pl/sql異常處理

*/

--預定義的異常
DECLARE
  V_SALARY EMPLOYEES.SALARY%TYPE;
BEGIN
  --查詢結果會返回多條資料
  SELECT SALARY INTO V_SALARY FROM EMPLOYEES WHERE EMPLOYEE_ID > 100;
  DBMS_OUTPUT.PUT_LINE('salary=' || V_SALARY);
EXCEPTION
  WHEN TOO_MANY_ROWS THEN
    DBMS_OUTPUT.PUT_LINE('輸出的行數太多了!!');
  WHEN OTHERS THEN
    DBMS_OUTPUT.PUT_LINE('出現其他型別的異常了!!');
END;


--非預定義的異常
DECLARE 
--宣告一個異常型別的變數
e_deleteEmpid_exception EXCEPTION;
--讓宣告的異常變數和錯誤號關聯起來
PRAGMA EXCEPTION_INIT(e_deleteEmpid_exception, -02292);
BEGIN
DELETE FROM employees WHERE employee_id = 100; --執行刪除操作的時候，會報錯，錯誤號是-02292
EXCEPTION 
  --使用異常變數
  WHEN e_deleteEmpid_exception THEN dbms_output.put_line('違反完整性約束條件，因此不能刪除此使用者!!!');
END;

--使用者自定義的異常處理
DECLARE 
e_too_high_salary EXCEPTION;
v_salary employees.salary%TYPE;
BEGIN
  SELECT salary INTO v_salary FROM employees WHERE employee_id = 100;
  IF v_salary > 12000 THEN 
    RAISE e_too_high_salary; --RAISE關鍵字，類似於java中的丟擲異常
  END IF;
EXCEPTION 
  WHEN e_too_high_salary THEN dbms_output.put_line('薪水太高了!!!!');  
END;

--多個異常
DECLARE 
e_too_high_salary EXCEPTION;
v_salary employees.salary%TYPE;
e_deleteEmpid_exception EXCEPTION;
--讓宣告的異常變數和錯誤號關聯起來
PRAGMA EXCEPTION_INIT(e_deleteEmpid_exception, -02292);
BEGIN
  DELETE FROM employees WHERE employee_id = 100; --執行刪除操作的時候，會報錯，錯誤號是-02292
  SELECT salary INTO v_salary FROM employees WHERE employee_id = 100;
  IF v_salary > 12000 THEN 
    RAISE e_too_high_salary; --RAISE關鍵字
  END IF;
EXCEPTION 
  WHEN e_too_high_salary THEN dbms_output.put_line('薪水太高了!!!!'); 
  WHEN e_deleteEmpid_exception THEN dbms_output.put_line('違反完整性約束條件，因此不能刪除此使用者!!!');
  WHEN OTHERS THEN dbms_output.put_line('發生其他型別的異常了!!!'); 
END;

--多個異常
DECLARE 
e_too_high_salary EXCEPTION;
v_salary employees.salary%TYPE;
e_deleteEmpid_exception EXCEPTION;
--讓宣告的異常變數和錯誤號關聯起來
PRAGMA EXCEPTION_INIT(e_deleteEmpid_exception, -02292);
BEGIN
  SELECT salary INTO v_salary FROM employees WHERE employee_id = 100;
  IF v_salary > 12000 THEN 
    RAISE e_too_high_salary; --RAISE關鍵字
  END IF;
  DELETE FROM employees WHERE employee_id = 100; --執行刪除操作的時候，會報錯，錯誤號是-02292
  
EXCEPTION 
  WHEN e_too_high_salary THEN dbms_output.put_line('薪水太高了!!!!'); 
  WHEN e_deleteEmpid_exception THEN dbms_output.put_line('違反完整性約束條件，因此不能刪除此使用者!!!');
  WHEN OTHERS THEN dbms_output.put_line('發生其他型別的異常了!!!'); 
END;

/*

異常知識點的練習

*/

--通過 select ... into ... 查詢某人的工資, 若沒有查詢到, 則輸出 "未找到資料"
DECLARE
v_salary employees.salary%TYPE;
BEGIN
SELECT salary INTO v_salary FROM employees WHERE employee_id = -666;
dbms_output.put_line('salary = ' || v_salary);
EXCEPTION
  WHEN no_data_found THEN dbms_output.put_line('查無此人，未找到資料');
  WHEN OTHERS THEN dbms_output.put_line('其他型別的異常');
END; 

--更新指定員工工資，如工資小於300，則加100；對 NO_DATA_FOUND 異常, TOO_MANY_ROWS 進行處理
DECLARE 
v_salary employees.salary%TYPE;
v_employee_id employees.employee_id%TYPE := 100;
BEGIN
  --v_employee_id := 100;
  v_employee_id := 8899;
  SELECT salary INTO v_salary FROM employees WHERE 
  employee_id = v_employee_id;
  --employee_id < v_employee_id;
  dbms_output.put_line('salary = ' || v_salary);
  IF v_salary < 300 THEN 
    UPDATE employees SET salary = salary + 100 WHERE employee_id = v_employee_id;
  END IF;
EXCEPTION
  WHEN NO_DATA_FOUND THEN dbms_output.put_line('查無此人，未找到資料');  
  WHEN TOO_MANY_ROWS THEN dbms_output.put_line('輸出的行數太多了!!!');
  WHEN OTHERS THEN dbms_output.put_line('其他型別的異常!!!');
END;

--自定義異常: 更新指定員工工資，增加100；若該員工不存在則丟擲使用者自定義異常: no_result
DECLARE
  --自定義異常                                   
  E_NO_RESULT EXCEPTION;
BEGIN
  UPDATE EMPLOYEES SET SALARY = SALARY + 100 WHERE EMPLOYEE_ID = 1001;
  --使用隱式遊標, 丟擲自定義異常
  IF SQL%NOTFOUND THEN
    RAISE E_NO_RESULT;
  END IF;
EXCEPTION
  --處理程式丟擲的異常
  WHEN E_NO_RESULT THEN
    DBMS_OUTPUT.PUT_LINE('更新失敗');
END;