group by sale.empid,employee.empname--,sum(salesum)

------解决方案--------------------
SQL code

create procedure ListSaleSum
@year int,
@month int
as
begin
    select 
        sale.empid as 员工编号,
        employee.empname as 员工姓名,
        sum(salesum) as 销售合计
    from sale,employee
    where sale.empid=employee.empid
    and year(saledate)=@year
    and month(saledate)=@month
    group by sale.empid,employee.empname
    
    --,sum(salesum) 这里不需要的
end