plsql – PL / SQL检查查询是否返回空

我正在编写一个程序,我需要检查我的select查询是否返回一个空的记录.
(在这个例子中是否没有x,y架)

我怎样才能做到这一点？

我试过这个：

temp shelves.loadability%TYPE := NULL;
BEGIN

select loadability into temp from shelves where rownumber = x and columnnumber = y;
IF temp IS NOT NULL THEN
/* do something when it's not empty */
ELSE
/* do the other thing when it's empty */
END IF;

但是,如果没有工作,第二个分支

编辑：

哦,这样很容易

temp shelves.loadability%TYPE;
BEGIN

select count(*) into temp from shelves where rownumber = x and columnnumber = y;
IF temp != 0 THEN
/* do something when it's not empty */
ELSE
/* do the other thing when it's empty */
END IF;

END;

解决方法

使用异常处理程序

Begin
  select column
  into variable
  from table
  where ...;

  -- Do something with your variable

exception
 when no_data_found then
    -- Your query returned no rows --

 when too_many_rows
    -- Your query returned more than 1 row --

end;