[Mono-list] Re: MySQLDataReader.Read Exception

[Daniel Morgan]

In MySqlTypes.cs, in
object ConvertDbTypeToSystem (MySqlEnumFieldTypes mysqlFieldType,
						DbType typ, String myValue)

I can have a special case, for when the date is '0000-00-00 00:00:00', i can
set the DateTime to DBNull.Value.

switch(mysqlFieldType) {
	case MySqlEnumFieldTypes.FIELD_TYPE_TIMESTAMP:
		if(myValue.Equals("00000000000000"))
			return DBNull.Value;
		break;
	// new code BEGIN
	case MySqlEnumFieldTypes.FIELD_TYPE_DATETIME:
		if(myValue.Equals("0000-00-00 00:00:00"))
			return DBNull.Value;
		break;
	// new code END
}

I think the minimum DateTime that can be used is '0001-01-01 00:00:00'.

-----Original Message-----
From: mono-list-admin@ximian.com [mailto:mono-list-admin@ximian.com]On
Behalf Of Vincent Daron
Sent: Thursday, January 09, 2003 4:02 PM
To: Jeremy N. Morgan
Cc: mono-list@ximian.com
Subject: RE: [Mono-list] Re: MySQLDataReader.Read Exception


Tanks,

The response is simple: do not use date = 0000-00-00 00:00:00 with
MySQL, use 1900-01-01 instead. ;-)

But the problem is the exception in the DataReader.

> Select if(date1='', '1900-01-01', date1) as date1 from table1;

Is this a standard SQL 92 Select ?

Thanks a lot

Vincent

On Thu, 2003-01-09 at 19:28, Jeremy N. Morgan wrote:
> As far as I can tell, the problem appears to be that MySQL doesn't use
> an actual date to display an empty string.  MySQL uses 0000-00-00,
> unlike the other databases I am familiar with (MS-SQL and Oracle), which
> use 1900-01-01, a valid date.  When the MySQLreader gets the 0000-00-00,
> it tries to cast it into a datetime value and fails (with 0000-00-00 not
> being a valid date).
>
> Try setting your select statement to do an IF(expr1,expr2,expr3) when
> returning that field to return a valid date if it encounters an empty
> string like:
>
> Select if(date1='', '1900-01-01', date1) as date1 from table1;
>
>
> Not knowing C# very well, I don't know how to fix this in the
> MySQLReader code, but my hunch is that the MySQLReader just needs a
> datetime '' handler.  If it was based on the SQLDataReader, it probably
> doesn't have one because SQLDataReader doesn't need one since it would
> only ever get a valid date or null.
>
> Does that help?
>
> Jeremy N. Morgan
>
>
> -----Original Message-----
> From: Rodrigo Moya [mailto:rodrigo@ximian.com]
> Sent: Wednesday, January 08, 2003 4:24 PM
> To: Vincent Daron
> Cc: mono-list@ximian.com
> Subject: [Mono-list] Re: MySQLDataReader.Read Exception
>
>
> On Wed, 2003-01-08 at 22:03, Vincent Daron wrote:
> > hello
> >
> > I've got an invalid cast exception in MySQLDataReader.Read() while
> > reading a row containing a DateTime field = 0000-00-00 00:00:00.
> >
> > It's less than DateTime.MinValue and I suppose that the problem is the
>
> > same with value bigger than MaxValue.
> >
> > Any idea ?
> >
> not sure what it is, so forwarding to the mono list.
>
> cheers
--
Vincent Daron <vdaron@ask.be>
ASK sa


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