EntityFramework异常The specified cast from a materialized 'System.Double' type to the 'System.Single' type is not valid.

实体类：

    public class ReportEntity
    {
        public string FactorName { get; set; }
        public double MaxVal { get; set; }
        public double MinVal { get; set; }
        public double AvgVal { get; set; }
        public string UpdateTime { get; set; }
        public string Unit { get; set; }
        public int DecimalDigit { get; set; }
    }

SQL语句

            string sqlstr = "   select b.FactorName,cast(MAX(a.Val) as float) as MaxVal,cast(MIN(a.Val) as float) as MinVal,cast(AVG(a.Val) as float) as AvgVal,"
                            + strTime + " as UpdateTime,b.Unit,b.DecimalDigit "
                            + "    from Instrument_Data a,Factor b   "
                            + " where a.UpdateTime between '" + dtBegin + "' and '" + dtEnd + "'    "
                            + " and a.FactorID = b.FactorID   "
                            + " group by b.FactorName,b.Unit, " + strTime + ",b.DecimalDigit  "
                            + " order by b.FactorName,b.Unit," + strTime + ",b.DecimalDigit  ";

            using (var db = new DAL.WSIPCContext())
            {
                var result3 = db.Database.SqlQuery<Entity.ReportEntity>(sqlstr);
                this.lsvData.Items.Clear();
                foreach (Entity.ReportEntity i in result3)
                {
                    ListViewItem item = new ListViewItem();
                    item.SubItems.Clear();
                    item.Text = i.UpdateTime;
                    item.SubItems.Add(i.FactorName);
                    string format = "#0.".PadRight(i.DecimalDigit + 3, '0');
                    item.SubItems.Add(i.MaxVal.TryToDoubleStr(format));
                    item.SubItems.Add(i.MinVal.TryToDoubleStr(format));
                    item.SubItems.Add(i.AvgVal.TryToDoubleStr(format));
                    item.SubItems.Add(i.Unit);
                    this.lsvData.Items.Add(item);
                }
            }

将double换成float出现错误。EF使用System.Double对应SQLServer中的float。

重点关注：此处对SQL语句的结果也有要求，结果必须转换为float，才能与实体类映射成功！