Question

这些是我创建的表的列表，并为创建的表插入了值：

CREATE TABLE DEPARTMENT
(DEPARTMENT_ID NUMBER PRIMARY KEY,
 DEPARTMENT_NAME VARCHAR(30) NOT NULL
 );

 CREATE TABLE JOBS
 (JOB_ID NUMBER PRIMARY KEY,
  JOB_TITLE VARCHAR(35) NOT NULL,
  MIN_SALARY DECIMAL NOT NULL,
  MAX_SALARY DECIMAL NOT NULL
  );

 CREATE TABLE EMPLOYEES
(EMPLOYEE_ID NUMBER PRIMARY KEY,
 FIRST_NAME VARCHAR(20) NOT NULL,
 LAST_NAME VARCHAR(25) NOT NULL,
 EMAIL VARCHAR(25) NOT NULL,
 PHONE_NUMBER VARCHAR(20) NOT NULL,
 HIRE_DATE DATE NOT NULL,
 JOB_ID NUMBER NOT NULL,
 SALARY DECIMAL NOT NULL,
 DEPARTMENT_ID NUMBER NOT NULL,
 CONSTRAINT emp_job_fk FOREIGN KEY(JOB_ID) REFERENCES JOBS(JOB_ID),
 CONSTRAINT emp_department_fk FOREIGN KEY(DEPARTMENT_ID) REFERENCES DEPARTMENT(DEPARTMENT_ID)
 );

INSERT INTO DEPARTMENT (DEPARTMENT_ID,DEPARTMENT_NAME)
VALUES(1,'IT');
INSERT INTO DEPARTMENT (DEPARTMENT_ID,DEPARTMENT_NAME)
VALUES(2,'Sales');

INSERT INTO JOBS (JOB_ID,JOB_TITLE,MIN_SALARY,MAX_SALARY)
VALUES (1,'IT Administrator',250000.00,50000.00);
INSERT INTO JOBS (JOB_ID,JOB_TITLE,MIN_SALARY,MAX_SALARY)
VALUES (2,'Salesman',200000.00,40000.00);

INSERT INTO EMPLOYEES (EMPLOYEE_ID,FIRST_NAME,LAST_NAME,EMAIL,PHONE_NUMBER,HIRE_DATE,JOB_ID,SALARY,DEPARTMENT_ID)
VALUES (1,'Tony','Starc','starc@gmail.com','0123456789',TO_DATE('15/1/2008','DD/MM/YYYY'),1,45000.00,1);
INSERT INTO EMPLOYEES (EMPLOYEE_ID,FIRST_NAME,LAST_NAME,EMAIL,PHONE_NUMBER,HIRE_DATE,JOB_ID,SALARY,DEPARTMENT_ID)
VALUES (2,'Bruce','Wayne','bruce@gmail.com','0123456788',TO_DATE('15/1/2009','DD/MM/YYYY'),1,40000.00,1);
INSERT INTO EMPLOYEES (EMPLOYEE_ID,FIRST_NAME,LAST_NAME,EMAIL,PHONE_NUMBER,HIRE_DATE,JOB_ID,SALARY,DEPARTMENT_ID)
VALUES (3,'Larry','Ellison','larry@gmail.com','0123456787',TO_DATE('15/1/2010','DD/MM/YYYY'),1,30000.00,1);
INSERT INTO EMPLOYEES (EMPLOYEE_ID,FIRST_NAME,LAST_NAME,EMAIL,PHONE_NUMBER,HIRE_DATE,JOB_ID,SALARY,DEPARTMENT_ID)
VALUES (4,'Steve','Jobs','steve@gmail.com','0123456786',TO_DATE('15/1/2011','DD/MM/YYYY'),2,35000.00,2);
INSERT INTO EMPLOYEES (EMPLOYEE_ID,FIRST_NAME,LAST_NAME,EMAIL,PHONE_NUMBER,HIRE_DATE,JOB_ID,SALARY,DEPARTMENT_ID)
VALUES (5,'Remy','Lebeau','remy@gmail.com','0123456785',TO_DATE('15/1/2012','DD/MM/YYYY'),2,30000.00,2);
INSERT INTO EMPLOYEES (EMPLOYEE_ID,FIRST_NAME,LAST_NAME,EMAIL,PHONE_NUMBER,HIRE_DATE,JOB_ID,SALARY,DEPARTMENT_ID)
VALUES (6,'Clark','Kent','clark@gmail.com','0123456784',TO_DATE('15/1/2013','DD/MM/YYYY'),2,20000.00,2);

现在，在我的任务中，我被要求解决以下问题：

编写一个名为fn_emps_per_dept_jc450912的函数，以使用给定的DEPARTMENT_ID检索EMPLOYEE_ID，FIRST_NAME，LAST_NAME和JOB_TITLE。此函数应将DEPARTMENT_ID作为输入参数，此函数应具有EMPLOYEE_ID，FIRST_NAME，LAST_NAME和JOB_TITLE作为输出参数。如果找到则应返回TRUE，如果未找到则返回FALSE。

为了显示特定部门员工的信息，我写了以下功能：

CREATE OR REPLACE FUNCTION fn_emps_per_dept_jc450912 (f_dept_id NUMBER)
RETURN SYS_REFCURSOR 
AS
emp_details SYS_REFCURSOR;
BEGIN
OPEN emp_details 
FOR
SELECT EMPLOYEE_ID,FIRST_NAME,LAST_NAME,JOB_TITLE
FROM EMPLOYEES,JOBS,DEPARTMENT
WHERE DEPARTMENT.DEPARTMENT_ID = EMPLOYEES.DEPARTMENT_ID
AND JOBS.JOB_ID = EMPLOYEES.JOB_ID
AND EMPLOYEES.DEPARTMENT_ID = f_dept_id;
RETURN emp_details;
EXCEPTION
WHEN NO_DATA_FOUND
THEN
DBMS_OUTPUT.PUT_LINE('Department not available');
END fn_emps_per_dept_jc450912;

VARIABLE e REFCURSOR
EXECUTE :e := fn_emps_per_dept_jc450912(1); 

PRINT e;

EMPLOYEE_ID FIRST_NAME           LAST_NAME                 JOB_TITLE
----------- -------------------- ------------------------- ----------------------------
          1 Tony                 Starc                     IT Administrator
          2 Bruce                Wayne                     IT Administrator
          3 Larry                Ellison                   IT Administrator

然后我尝试插入无效的部门编号：

VARIABLE e REFCURSOR
EXECUTE :e := fn_emps_per_dept_jc450912(5); 

PRINT e;

我有以下3个问题：

为什么空白？可能的错误在哪里？
该问题要求 EMPLOYEE_ID，FIRST_NAME，LAST_NAME和JOB_TITLE应为输出参数。但我将 EMPLOYEE_ID，FIRST_NAME，LAST_NAME和JOB_TITLE 作为 SYS_REFCURSOR 返回。那么根据输出参数的问题，我的方法是否正确？
我需要修复哪部分代码？如何重写这个功能？

Answer 1

打开NO_DATA_FOUND时不会引发{p> REF CURSOR。因此，您可以使用以下方法。

将department_id的员工数存储到变量中。如果是count of employees = 0，请明确提出NO_DATA_FOUND。
在Exception块中，打开另一个返回a的游标消息而不是原始列。

这是修改后的功能。

CREATE OR REPLACE FUNCTION fn_emps_per_dept_jc450912(
    f_dept_id NUMBER)
  RETURN SYS_REFCURSOR
AS
  emp_details SYS_REFCURSOR;
  v_emp_id_count NUMBER;
BEGIN
  SELECT COUNT(EMPLOYEES.employee_id)
  INTO v_emp_id_count
  FROM EMPLOYEES,
    JOBS,
    DEPARTMENT
  WHERE DEPARTMENT.DEPARTMENT_ID = EMPLOYEES.DEPARTMENT_ID
  AND JOBS.JOB_ID                = EMPLOYEES.JOB_ID
  AND EMPLOYEES.DEPARTMENT_ID    = f_dept_id;
  IF v_emp_id_count                = 0 THEN
    RAISE NO_DATA_FOUND;
  END IF;
  OPEN emp_details FOR SELECT EMPLOYEE_ID,
  FIRST_NAME,
  LAST_NAME,
  JOB_TITLE FROM EMPLOYEES,
  JOBS,
  DEPARTMENT WHERE DEPARTMENT.DEPARTMENT_ID = EMPLOYEES.DEPARTMENT_ID 
  AND JOBS.JOB_ID = EMPLOYEES.JOB_ID AND EMPLOYEES.DEPARTMENT_ID = f_dept_id;
  RETURN emp_details;
EXCEPTION
WHEN NO_DATA_FOUND THEN
  OPEN emp_details FOR SELECT 'Department not available' MESSAGE FROM DUAL;
  RETURN emp_details;
END fn_emps_per_dept_jc450912;
/

因此对于第二种情况（dept_id = 5），来自PRINT的输出将是。

MESSAGE                  
------------------------ 
Department not available

编写一个函数来显示基于Oracle中特定部门的员工信息？

1 个答案: