public class SqlTypeMapper
    {
        public Type GetClrType(string sqlTypeName, bool isNullable)
        {
            Type baseType = this.GetClrBaseType(sqlTypeName);

            if (baseType.IsValueType && isNullable)
                return typeof(Nullable<>).MakeGenericType(baseType);

            return baseType;
        }
        private Type GetClrBaseType(string sqlTypeName)
        {
            switch (sqlTypeName)
            {
                case "bigint":
                    return typeof(long);
                case "binary":
                case "image":
                case "rowversion":
                case "timestamp":
                case "varbinary":
                    return typeof(byte[]);
                case "bit":
                    return typeof(bool);
                case "char":
                case "nchar":
                case "ntext":
                case "nvarchar":
                case "text":
                case "varchar":
                    return typeof(string);
                case "date":
                case "datetime":
                case "datetime2":
                case "smalldatetime":
                    return typeof(DateTime);
                case "datetimeoffset":
                    return typeof(DateTimeOffset);
                case "decimal":
                case "money":
                case "numeric":
                case "smallmoney":
                    return typeof(decimal);
                case "float":
                    return typeof(double);
                case "int":
                    return typeof(int);
                case "real":
                    return typeof(float);
                case "smallint":
                    return typeof(short);
                case "time":
                    return typeof(TimeSpan);
                case "tinyint":
                    return typeof(byte);
                case "uniqueidentifier":
                    return typeof(Guid);
                default:
                    throw new InvalidOperationException("Unknown type '" + sqlTypeName + "'.");
            }
        }
    }