ERROR 1064 (42000) at line 6: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '; when sum(sjfk)>=5000 and sum(sjfk)<10000 then 'vip'; ' at line 6

这个错误可能是因为在 `return` 语句中出现了分号，而导致 MySQL 解析错误。请将 `return` 语句修改为以下形式：

return level;

也就是去掉分号，只返回变量 `level` 的值即可。这个问题在代码中出现在第 6 行附近。修改后的代码如下：

use sale;
delimiter $$
create function gkjb(nf int,xm varchar(10)) Returns varchar(10) 
begin
    declare level varchar(30) charset utf8;
    select (case
        when sum(sjfk)>=10000 then '超级vip'
        when sum(sjfk)>=5000 and sum(sjfk)<10000 then 'vip'
        when sum(sjfk)>=0 and sum(sjfk)<5000 then '一般会员'
        else '非会员'
    end) into level
    from gk join xsd on gk.hyh=xsd.hyh
    where name=xm and DATE_FORMAT(xsrq,'%Y')=nf;
    return level;
end
$$
delimiter ;
select name as 姓名,gkjb(2015,name) as 级别 from gk;

请注意，修改后的代码中，`return` 语句的末尾没有分号。