ORACLE PL/SQL 函数创建成功但执行体不工作

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'),2,35000.00,2);

现在在我的作业问题中，我被要求解决以下问题： 编写一个名为 fn_emps_per_dept_jc450912 的函数来检索具有给定 DEPARTMENT_ID 的 EMPLOYEE_ID、FIRST_NAME、LAST_NAME 和 JOB_TITLE。这个函数应该有 DEPARTMENT_ID 作为输入参数，这个函数应该有 EMPLOYEE_ID、FIRST_NAME、LAST_NAME 和 JOB_TITLE 作为输出参数。如果找到它应该返回 TRUE，如果没有找到则返回 FALSE。

为了显示特定部门员工的信息，我写了以下函数：

CREATE OR REPLACE FUNCTION fn_emps_per_dept_jc450912 (f_dept_id IN NUMBER,f_emp_id OUT NUMBER,f_first_name OUT VARCHAR,f_last_name OUT VARCHAR,f_job_title OUT VARCHAR)
RETURN BOOLEAN
AS
BEGIN
SELECT EMPLOYEE_ID,FIRST_NAME,LAST_NAME,JOB_TITLE
INTO f_emp_id,f_first_name,f_last_name,f_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 TRUE;
EXCEPTION
WHEN NO_DATA_FOUND
THEN
DBMS_OUTPUT.PUT_LINE('Employee not found');
RETURN FALSE;
END fn_emps_per_dept_jc450912;

Function FN_EMPS_PER_DEPT_JC450912 compiled

从上面可以看出，函数已经编译成功了。

然后我尝试执行函数：

DECLARE
f_dept_id NUMBER;
f_emp_id NUMBER;
f_first_name VARCHAR(30) ;
f_last_name VARCHAR(30) ;
f_job_title VARCHAR(30);
f_return BOOLEAN;
BEGIN
f_dept_id := 1;
f_return := fn_emps_per_dept_jc450912(f_dept_id,f_emp_id,f_first_name,f_last_name,f_job_title);
DBMS_OUTPUT.PUT_LINE('Employee_ID: ' || f_emp_id);
DBMS_OUTPUT.PUT_LINE('First Name: ' || f_first_name);
DBMS_OUTPUT.PUT_LINE('Last Name: ' || f_last_name);
DBMS_OUTPUT.PUT_LINE('Job: ' || f_job_title);
END;

我收到以下错误：

Error report -
ORA-01422: exact fetch returns more than requested number of rows
ORA-06512: at "SYSTEM.FN_EMPS_PER_DEPT_JC450912", line 5
ORA-06512: at line 10
01422. 00000 -  "exact fetch returns more than requested number of rows"
*Cause:    The number specified in exact fetch is less than the rows returned.
*Action:   Rewrite the query or change number of rows requested

我需要执行体的解决方案代码来修复这个错误。

Answer 1

首先请使用现代连接语法（自 92 以来的 ANSI 标准！）。

所以你的 SELECT 应该是：

SELECT EMPLOYEE_ID,FIRST_NAME,LAST_NAME,JOB_TITLE
INTO f_emp_id,f_first_name,f_last_name,f_job_title
FROM EMPLOYEES INNER JOIN JOBS ON JOBS.JOB_ID = EMPLOYEES.JOB_ID
INNER JOIN DEPARTMENT ON DEPARTMENT.DEPARTMENT_ID = EMPLOYEES.DEPARTMENT_ID
WHERE EMPLOYEES.DEPARTMENT_ID = f_dept_id;

接下来当你遇到这样的问题时，你应该在查询窗口中运行查询，如下所示：

SELECT EMPLOYEE_ID,FIRST_NAME,LAST_NAME,JOB_TITLE
FROM EMPLOYEES INNER JOIN JOBS ON JOBS.JOB_ID = EMPLOYEES.JOB_ID
INNER JOIN DEPARTMENT ON DEPARTMENT.DEPARTMENT_ID = EMPLOYEES.DEPARTMENT_ID
WHERE EMPLOYEES.DEPARTMENT_ID = 1;

这将揭示问题的原因，因为输出看起来像这样

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

即字段 employees.department_id 不是唯一的。因此，在执行时，存储过程会尝试将多个值放入单个变量中。这是它无法做到的，因此出现了错误。程序编译成功，因为在编译时，程序可能不知道它会被传递一个导致结果集中有多个记录的参数。