返回函数中的计数 - Mysql

Question

我有一个复杂的SQL，希望有一个我可以调用的函数，它返回行数。

我写道：

BEGIN
    declare thetotal INT;
    select count(id) AS thetotal from countries where id = countryid;
    RETURN thetotal;
END;

但它不会让我从选择中返回。

Answer 1

改为使用SELECT..INTO：

BEGIN
    declare thetotal INT;
    select count(id) INTO thetotal from countries where id = countryid;
    RETURN thetotal;
END;

Answer 2

BEGIN
declare thetotal INT;
select @thetotal =count(id)  from countries where id = countryid;
RETURN thetotal;
END;