使用NBearMapping做测试，才发现SQL中的float不能被自动Map到实体类型为float字段中。
搜索了一下，才发现SQL中的float对应到C#的double，我晕了。

/// <summary>
        /// 数据库中与C#中的数据类型对照
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        private string ChangeToCSharpType(string type)
        {
            string reval = string.Empty;
            switch (type.ToLower())
            {
                case "int":
                    reval = "Int32";
                    break;
                case "text":
                    reval = "String";
                    break;
                case "bigint":
                    reval = "Int64";
                    break;
                case "binary":
                    reval = "System.Byte[]";
                    break;
                case "bit":
                    reval = "Boolean";
                    break;
                case "char":
                    reval = "String";
                    break;
                case "datetime":
                    reval = "System.DateTime";
                    break;
                case "decimal":
                    reval = "System.Decimal";
                    break;
                case "float":
                    reval = "System.Double";
                    break;
                case "image":
                    reval = "System.Byte[]";
                    break;
                case "money":
                    reval = "System.Decimal";
                    break;
                case "nchar":
                    reval = "String";
                    break;
                case "ntext":
                    reval = "String";
                    break;
                case "numeric":
                    reval = "System.Decimal";
                    break;
                case "nvarchar":
                    reval = "String";
                    break;
                case "real":
                    reval = "System.Single";
                    break;
                case "smalldatetime":
                    reval = "System.DateTime";
                    break;
                case "smallint":
                    reval = "Int16";
                    break;
                case "smallmoney":
                    reval = "System.Decimal";
                    break;
                case "timestamp":
                    reval = "System.DateTime";
                    break;
                case "tinyint":
                    reval = "System.Byte";
                    break;
                case "uniqueidentifier":
                    reval = "System.Guid";
                    break;
                case "varbinary":
                    reval = "System.Byte[]";
                    break;
                case "varchar":
                    reval = "String";
                    break;
                case "Variant":
                    reval = "Object";
                    break;
                default:
                    reval = "String";
                    break;
            }
            return reval;
        }