在此上下文中不允许出现错误“表、视图或序列引用“EMPLOYEES.EMP_NAME””

Question

create table Employees (emp_id number, emp_name varchar2(50), salary number, department_id number, DESIGNATION varchar2(50), DEVELOPED_TESTED varchar2(50)) ;

insert into Employees values(1,'ALex',10000,10,'Developer','VLC');
insert into Employees values(2,'Duplex',20000,20,'Developer','VLC');
insert into Employees values(3,'Charles',30000,30,'Tester','Tested_VLC');
insert into Employees values(4,'Demon',40000,40,'Tester ','Tested_VLC');
insert into employees values(5,'Chaem',5000,50,'Developer','');

要求：

如果指定为“开发者”并且开发测试列为空，我想返回 2。但是在输出中我得到的是 null 而不是 2。你能检查一下吗？

代码：

        create or replace FUNCTION calculate_royalty (
    i_empno IN NUMBER
    
) RETURN VARCHAR2 IS
  l_employee employees%ROWTYPE;
BEGIN 
  SELECT *
    INTO l_employee
    FROM
        employees
    WHERE  emp_id = i_empno; 
  IF l_employee.designation = 'Developer' THEN
    RETURN l_employee.developed_tested;
  ELSIF l_employee.designation = 'Developer' and l_employee.developed_tested is null THEN 
    RETURN 2;
  ELSE
    RETURN 1;
  END IF;
  
EXCEPTION WHEN NO_DATA_FOUND THEN
  RETURN 0;
END ;

从双重中选择 CALCULATE_ROYALTY(5)； -- 输出为 NULL，但理想情况下应该是 2。

Answer 1

只需将整行选择成一个变量，无需使用计数。使用NO_DATA_FOUND异常处理用户不存在的情况。

您的问题提到了与“版税”列相关的一些功能。您的测试用例中缺少这一点，但修改下面的代码应该是小菜一碟，以满足您的所有需求。

create or replace FUNCTION calculate_royalty (
    empno_i IN NUMBER
    -- don't use column names as names of input parameters, that is a recipe for disaster. Use prefix/suffix.
) RETURN VARCHAR2 IS
  lv_count NUMBER;
  l_employee employees%ROWTYPE;
BEGIN 
  SELECT *
    INTO l_employee
    FROM
        employees
    WHERE  emp_id = empno_i; 
  IF l_employee.designation = 'Developer' THEN
    RETURN l_employee.salary;
  ELSE
    RETURN 1;
  END IF;
  -- dbms_output just sends data to a buffer that you then print to the console. it cannot be used as a return value.
  --  RETURN dbms_output.put_line('Emp Name :'...
  
-- elsif needs to be followed by an expression. It cannot be followed by a RETURN keyword. Use "ELSE" instead if there is no condition.
-- elsif return 1;
EXCEPTION WHEN NO_DATA_FOUND THEN
  RETURN 0;
END ;
/

set serveroutput on size 999999
clear screen
BEGIN
  dbms_output.put_line('output for Developer: '|| calculate_royalty(EMPNO_I => 2));
  dbms_output.put_line('output for no Developer: '|| calculate_royalty(EMPNO_I => 3));
  dbms_output.put_line('output for non-existing user: '|| calculate_royalty(EMPNO_I => 10));
END;

output for Developer: 20000
output for no Developer: 1
output for non-existing user: 0


PL/SQL procedure successfully completed.