I guess what worries me most is not the problem with null dates etc, but the fact that
with one version of the connector I can cast a MySql date field straight into a .Net Date
field, but as soon as I upgrade to a new version of the connector my application crashes
when I attempt such a cast. It might be better if it failed to compile - at least I would
have a warning.
As I haven't been using Mysql with .Net for long I may have missed a big banner at some
point warning that this would happen. It is very disconcerting to have ones rock solid
application crash in a big heap when you haven't even touched any code. Surely
implementing changes like this is a "no no" for any provider? Why was this change
introduced anyway - the direct cast to a .Net date field worked perfectly, so why change
it ?
-----Original Message-----
From: Ben Reichelt [mailto:ben.reichelt@stripped]
Sent: 13 February 2005 16:28
To: dotnet@stripped
Subject: Re: Date casting problem
I wonder if using .net 2.0 will make this problem a little easier to
deal with, by using nullable value types, this way, if a date field is
null, you can have a null DateTime like this:
DateTime? dt = dr["myDateField"] as DateTime?;
On Sun, 13 Feb 2005 07:17:39 -0800, Jordan Sparks
<jsparks@stripped> wrote:
> I agree. I would like null dates as well, but there's no such thing as
> null dates in .NET. It was in the beta, but gone by production. The
> limiting factor is .NET. So use 1-1-1 as your 'null' date, and use
> internal logic to test for that value. But the data in the database
> should mirror that convention.
>
> Jordan Sparks
>
> -----Original Message-----
> From: Kevin Turner [mailto:kevin.turner@stripped]
> Sent: Sunday, February 13, 2005 7:10 AM
> To: dotnet@stripped
> Subject: RE: Date casting problem
>
> Thanks for the suggestion. I will try it.
>
> Dunno if I am storing illegal dates though really - more the fact that I
> want some date fields to be null. Surely if the database can store a
> value in a certain way, the connector should allow for it?
>
> -----Original Message-----
> From: Jordan Sparks [mailto:jsparks@stripped]
> Sent: 13 February 2005 14:57
> To: dotnet@stripped
> Subject: RE: Date casting problem
>
> Sorry, I don't know the vb syntax.
>
> Here's how I would do it in C#. First to a string, then to a .NET
> datetime, and finally to a string for display. Yes, you have to write a
> small function to do this for every incoming date, but you only have to
> write it once, and it's very small:
>
> public static DateTime GetDate(string myString){
> try{
> return (DateTime.Parse(myString));
> }
> catch{
> return DateTime.MinValue;
> }
> }
>
> And you would use it like this:
>
> strDate=MysqlIn.GetDate(dr["myDate"].ToString()).ToString("d");
>
> But the try statement can cause a slowdown, so you either fancy up my
> example to check for zeros instead of using a try, or you change your
> database columns to use 1-1-1 as the default. And really, how hard is
> this last to do? It's not the fault of the connector that you're trying
> to store illegal dates in your database. Keep it clean and just change
> your database.
>
> Jordan Sparks
>
> -----Original Message-----
> From: Kevin Turner [mailto:kevin.turner@stripped]
> Sent: Sunday, February 13, 2005 1:08 AM
> To: dotnet@stripped
> Subject: Date casting problem
>
> My database contains date fields that can legitimately contain "illegal"
> date values like 0000-00-00.
>
> Until recently I was using the ByteFx 0.76 version of the driver and
> everything worked fine worked fine. However, I was worried that
> connection pooling wasn't right so decided to convert to the new
> MySql.Data 1.0.4 version.
>
> My first problem was that have my web pages started to crash with a
> previously reported problem where the new driver does not like illegal
> (all zero) dates on the database. Well, on my application this is a
> common occurrence so I added the "Allow Zero Datetime" = "True" to my
> connection string to get around it.
>
> Now my problem is even worse. In many places in my code I have
> instructions like this:
>
> (assume "dr" is a datarow retrieved from a dataset)
>
> With Threading.Thread.CurrentThread
> strDate = CType(dr("myDate"), Date).ToString("d", .CurrentUICulture)
> End With
>
> This works perfectly with the ByteFx version and it converts the
> database date to a string format that is correct for the culture for the
> current thread (i.e. in the UK its dd/MM/yyyy format and in the US its
> M/d/yyyy format).
>
> With the new driver this statement is an illegal cast. All I can do is
> cast the database field to a Mysql.Data.MySqlDateTime - which does not
> have the appropriate ToString() method to use the threads culture.
>
> To say this is a disaster for me is an understatement. I have to revert
> to ByteFx 0.76 for now until somebody can tell me the solution. I know I
> can probably use the GetDateTime method on a reader, but what can I do
> with a datarow from a dataset ? Do I have to create my own function to
> cast to a Mysql.Datat.Type.MysqlDateTime, then use ToString, then cobble
> the correct date format from that ? Yuk !
>
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