Bug #82661 .net提供程序中MySqlDateTime类型的bug
Submitted: 20 Aug 2016 1:59 Modified: 23 Nov 2021 18:08
Reporter: blqw zhou Email Updates:
Status: Closed Impact on me:
Category:Connector / NET Severity:S2 (Serious)
Version:6.9.9 OS:Any
Assigned to: CPU Architecture:Any

[20 Aug 2016 1:59] blqw zhou
TypeCode GetTypeCode(); 返回 TypeCode.Empty
String ToString(IFormatProvider provider); 返回null
Object ToType(Type conversionType, IFormatProvider provider); 无论conversionType传入什么类型,均返回null


How to repeat:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
    class Program
        static void Main(string[] args)
            var mtime = new MySql.Data.Types.MySqlDateTime(DateTime.Now);
            var time = DateTime.Now;
            Console.WriteLine(Convert(mtime)); //null

            Console.WriteLine(GetString(mtime)); //null

            Console.WriteLine(System.Convert.ToString(mtime)); //null

        static string GetString(object obj)
            if (obj is IFormattable)
                return ((IFormattable)obj).ToString(null, null);
            if (obj is IConvertible)
                return ((IConvertible)obj).ToString(null);
            return obj.ToString();

        static object Convert(IConvertible obj)
            switch (obj.GetTypeCode())
                case TypeCode.Empty:
                    return null;
                case TypeCode.Object:
                    return obj.ToType(typeof(object), null);
                case TypeCode.DBNull:
                    return DBNull.Value;
                case TypeCode.Boolean:
                    return obj.ToBoolean(null);
                case TypeCode.Char:
                    return obj.ToChar(null);
                case TypeCode.SByte:
                    return obj.ToSByte(null);
                case TypeCode.Byte:
                    return obj.ToByte(null);
                case TypeCode.Int16:
                    return obj.ToInt16(null);
                case TypeCode.UInt16:
                    return obj.ToUInt16(null);
                case TypeCode.Int32:
                    return obj.ToInt32(null);
                case TypeCode.UInt32:
                    return obj.ToUInt32(null);
                case TypeCode.Int64:
                    return obj.ToInt64(null);
                case TypeCode.UInt64:
                    return obj.ToUInt64(null);
                case TypeCode.Single:
                    return obj.ToSingle(null);
                case TypeCode.Double:
                    return obj.ToBoolean(null);
                case TypeCode.Decimal:
                    return obj.ToDecimal(null);
                case TypeCode.DateTime:
                    return obj.ToDateTime(null);
                case TypeCode.String:
                    return obj.ToString(null);
                    throw new InvalidCastException();


Suggested fix:
TypeCode GetTypeCode() 
returns TypeCode.DateTime;

String ToString(IFormatProvider provider); 
returns ((DateTime)value).ToString(provider);

Object ToType(Type conversionType, IFormatProvider provider); 
if (conversionType == typeof(DateTime)) return (DateTime)value;
if (conversionType == typeof(string)) return ((DateTime)value).ToString(provider)
if (conversionType == typeof(object)) return this;
if (conversionType == typeof(MySqlDateTime)) return this;
throw new InvalidCastException();
[20 Aug 2016 1:59] blqw zhou
my email : blqw@live.com
[22 Aug 2016 6:37] Chiranjeevi Battula
Hello blqw,

Thank you for the bug report and test case.
Verified this behavior on Visual Studio 2013 (C#.Net) and Connector/NET 6.9.9 version.

[23 Nov 2021 18:08] Christine Cole
Posted by developer:
Fixed as of the upcoming MySQL Connector/NET 8.0.28 release, and here's the proposed changelog entry from the documentation team:

A complete IConvertible implementation for the MySqlDateTime class was
missing from the .NET provider.

Thank you for the bug report.