PLS-00302：必须声明组件 - 无法解析

Question

我在SQL开发人员中尝试了以下程序并面临一些问题：

declare
  cursor emp_complex_cur is
    select e.fname,d.dlocation
      from employee e, dept_location d
     where e.dno=d.dnumber;
  emp_max_id integer;
  type emp_complex_rec is record(rname employee.fname%type,rlocation dept_location.dlocation%type);
begin
  open emp_complex_cur;
  for emp_complex_rec in emp_complex_cur loop
    fetch emp_complex_cur into emp_complex_rec;
    dbms_output.put_line('The employee id is: '||emp_complex_rec.rname||' and the employee''s location is '||emp_complex_rec.rlocation);
  close emp_complex_cur;
end;

我收到错误以声明变量rname，尽管它已在记录中正确声明。

Answer 1

尝试：

begin
  for emp_complex_rec in (select e.fname,
                                 d.dlocation
                            from employee e
                            INNER JOIN dept_location d
                              ON (e.dno = d.dnumber))
  loop
    dbms_output.put_line('The employee id is: ' ||
                         emp_complex_rec.rname ||
                         ' and the employee''s location is ' ||
                         emp_complex_rec.rlocation);
  end loop;
end;

原始代码的问题在于emp_complex_rec作为一种类型的定义与emp_complex_rec的定义作为游标循环变量发生冲突。也不需要显式游标定义 - IMO将SELECT置于FOR循环中更容易，更清晰。

分享并享受。

Answer 2

光标中列的名称与您在输出行中调用的名称不同，我猜你正在使用的循环是弄乱你的代码。实际上，它可能更简单：

declare
  cursor emp_complex_cur is
    select e.fname,d.dlocation
      from employee e, dept_location d
     where e.dno=d.dnumber;
  emp_max_id integer;
begin
  for emp_complex_rec in emp_complex_cur loop
    dbms_output.put_line('The employee id is: '||emp_complex_rec.fname||' and the employee''s location is '||emp_complex_rec.dlocation);
  end loop;
end;

Answer 3

你似乎对一些不同的技术感到困惑。

---

选项＃1 - 手动获取显式游标

declare
  cursor emp_complex_cur is
    select e.fname,d.dlocation
      from employee e, dept_location d
     where e.dno=d.dnumber;
  emp_max_id integer;
  type emp_complex_typ is record(rname employee.fname%type,rlocation dept_location.dlocation%type);
  --A variable must be declared of the type you've created
  emp_complex_rec emp_complex_typ;
begin
  open emp_complex_cur;
  --Initial fetch is needed
  fetch emp_complex_cur into r_complex_rec;
  while emp_complex_cur%found loop
    fetch emp_complex_cur into r_complex_rec;
  end loop;
  close emp_complex_cur;
  dbms_output.put_line('The employee id is: '||emp_complex_rec.rname||' and the employee''s location is '||emp_complex_rec.rlocation);
end;

---

选项＃2 - 使用for循环

获取显式游标

declare
  cursor emp_complex_cur is
    select e.fname,d.dlocation
      from employee e, dept_location d
     where e.dno=d.dnumber;
begin
  --no "open" required
  for emp_complex_rec in emp_complex_cur loop
    --no "fetch" required
    null;
  end loop;
  --no "close" required
  dbms_output.put_line('The employee id is: '||emp_complex_rec.rname||' and the employee''s location is '||emp_complex_rec.rlocation);
end;

---

选项＃3 - 使用for循环

获取隐式游标

请参阅@BobJarvis提供的答案

---

选项＃4 - 显式游标仅获取一次

对于这种仅检索单个记录的情况，我更喜欢使用显式游标和单个提取。如果您的查询返回1行或100，则无关紧要，因为您只执行一行。为什么要遍历你要忽略的所有行？

declare
  cursor emp_complex_cur is
    select e.fname,d.dlocation
      from employee e, dept_location d
     where e.dno=d.dnumber;
  emp_complex_rec emp_complex_cur%rowtype;
begin
  open emp_complex_cur;
  fetch emp_complex_cur into r_complex_rec;
  close emp_complex_cur;
  dbms_output.put_line('The employee id is: '||emp_complex_rec.fname||' and the employee''s location is '||emp_complex_rec.dlocation);
end;