for循环中的if else语句

Posted 2023-03-28

【中文标题】for循环中的if else语句

【英文标题】：If else statement in for loop

【发布时间】：2012-09-17 11:16:51

【问题描述】：

是否有可能在 for 循环中设置 if else 条件

例如

  IF (emp_no IS NULL) then
 for i in (select * from employees where emp_no= p_retval)
else
 for i in (select * from employees where emp_no= p_retval_withcond)
end if;

当我尝试上述方法时，我遇到了编译错误。

问候

【参考方案1】：

结构如下

IF (emp_no IS NULL) then
  for i in (select * from employees where emp_no= p_retval)
  loop
    -- loop actions
  end loop;
else
  for i in (select * from employees where emp_no= p_retval_withcond)
  loop
    -- second loop actions
  end loop;
end if;

【参考方案2】：

for 循环是不可能的，但如果你在循环中的操作在这两种情况下是相似的，我会用光标来做。

declare
cursor c1 is select * from employees where emp_no= p_retval;
cursor c2 is select * from employees where emp_no= p_retval_withcond;
ligne employees%rowtype;
.....
begin
   IF (emp_no IS NULL) then
      open c1;
   ELSE
      open C2;
   END IF;
   loop
      IF (emp_no IS NULL) then
         fetch C1 into ligne;
         exit when c1%notfound;
      ELSE
         fetch C2 into ligne;
         exit when c2%notfound;
      END IF;
      -- loop actions
      ....  
   end loop;
   IF (emp_no IS NULL) then
      close c1;
   ELSE
      close C2;
   END IF;
end;