菜鸟遇到个问题求救！

菜鸟遇到个问题 我写了个存储过程 分页的 目的是 从一个表 根据不同的分类来查询并且分页
前3个是分页的设置 第四个 是分类的 数据 第五个 是分类的子项 每次运行报错 无法将 'y'转换为int ALTER procedure [dbo].[fyinnovationbyzitem](@pagesize int,@currpage int,@totalrecords int output,@zid int,@zitem char)
as
begin
declare @total int;
set @total = (select COUNT(*) from Innovation where Cast(@zitem as nvarchar(50)) = @zid);
set @totalrecords = @total;
select top(@pagesize) * from Innovation where Id not in (select top((@currpage - 1)*@pagesize) Id from Innovation where Cast(@zitem as nvarchar(50)) = @zid) and Cast(@zitem as nvarchar(50)) = @zid;
end下边是调用存储过程的代码
asp。netpublic IList<Innovation> fyinnovationbyzitem(int pagesize, int currpage, out int totalrecords,int zid,string zitem)
        {
            IList<Innovation> lt = new List<Innovation>();
            string cs = Dbunit.ConnectionString;
            SqlConnection conn = new SqlConnection(cs);
            SqlParameter[] sp = new SqlParameter[5];
            sp[0] = new SqlParameter("@pagesize", pagesize);
            sp[1] = new SqlParameter("@currpage", currpage);
            sp[2] = new SqlParameter("@totalrecords", SqlDbType.Int, 4);
            sp[2].Direction = ParameterDirection.Output;
            sp[3] = new SqlParameter("@zid", zid);
            sp[4] = new SqlParameter("@zitem", zitem);
            using (SqlDataReader sdr = Dbunit.ExecuteReader("fyinnovationbyzitem", CommandType.StoredProcedure, sp))
            {
                if (sdr != null)
                {
                    Innovation inn = null;
                    while (sdr.Read())
                    {
                        inn = new Innovation();
                        inn.Id = sdr.GetInt32(0);
                        inn.Img = sdr.GetString(1);
                        inn.Contents = sdr.GetString(2);
                        inn.Peiyang = sdr.GetInt32(3);
                        inn.Keyan = sdr.GetInt32(4);
                        inn.Lingyu = sdr.GetInt32(5);
                        inn.State = sdr.GetInt32(6);
                        inn.Shengyuan = sdr.GetInt32(7);
                        inn.Year = sdr.GetString(8);
                        inn.Click = sdr.GetInt32(9);
                        inn.Title = sdr.GetString(10);
                        lt.Add(inn);
                    }
                }
            }
            totalrecords = Convert.ToInt32(sp[2].Value);
            return lt;
        }