possible to insert NULL into datetime field via textbox 1

[johnc83]

Hi,

My title basically says it all. My datetime field is bound to a textbox. Entering dates is no problem, the update works but I need to be able to enter NULL if the user has accidentally saved a date in there and needs to remove it.

Im starting to think this isn't possible and I hope I am wrong.

Could someone advise please?

Thanks

John

.NET 2.0, Visual Studio 2005, SQL Server 2005 Express

 

[jebenson]

The only way I can think to do this is to save the values of the existing record in variables, delete the existing record and then insert a new record with the saved values, excluding the date value in question.



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[Kliot]

A null date is not a valid date so an error is thrown, I like you don't agree.

If you are using a TextBox and not a DateTimePicker, I have come up with a workaround. I haven't seen it documented anywhere so I'm not sure if there are any inherent problems with it but it works fine for me.

Select the Date TextBox and go to properties -> DataBindings -> Advanced. Now we want to set the Null Value to "", the problem is if we do that VS thinks we don't want to set a null value. So we need to set the null value to something. In the "Null Value:" Box enter something odd like "Rover" an odd string is just easy to search for later. Now in the Solution Explorer select the "Show All Files" Button and expand the form you are using and select the Form.Designer.vb file. Now do a search for "Rover" and you will come up with something like:

Me.ShipDateTextBox.DataBindings.Add(New System.Windows.Forms.Binding("Text", Me.OrdersBindingSource, "ShipDate", True, System.Windows.Forms.DataSourceUpdateMode.OnValidation, "Rover"))

Next simply remove the word Rover and leave the double quotes ""

Me.ShipDateTextBox.DataBindings.Add(New System.Windows.Forms.Binding("Text", Me.OrdersBindingSource, "ShipDate", True, System.Windows.Forms.DataSourceUpdateMode.OnValidation, ""))


Now if the date in the TextBox is removed the value goes back to Null.

Hope this helps
Perrin

 

[johnc83]

Hi Perrin, suprisingly that works perfect!! I have read so many pages hovering around the answer (giving workarounds etc..) but never anything that worked as it should but thanks to you I have found it!

Thank you so much. Really appreciate it.

Jebenson - thanks for your reply, I was doing something similar to your answer but appreciate the reply nonetheless.

thanks both of you.

John



.NET 2.0, Visual Studio 2005, SQL Server 2005 Express

 

[SgtJarrow]

Most Excellent......Thank you.

=======================================
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Robert L. Johnson III
CCNA, CCDA, MCSA, CNA, Net+, A+, CHDP
VB.NET Programmer

 

[Kliot]

John,

I'm glad it worked for you, I struggled with this problem for a while until I stummbled on this solution. I was also surprised how well it worked.

The only problem I have found and it's a minor one is if you later change the advanced databindings the null value changes will be overwritten and you will have to go through this process again.

Perrin