Date Unwanted Convert !

[Hamid.Khp]

Hi
First of all I should Thanks for your time .
When I change my Windows region To Persian , When i Want to add Date Value to my data table with Date Type , The Program See my Value As Hejri Calendar and convert it to gregorian calendar .
if i want to explain my problem :

Dim DataTable as new DataTable
 DataTable.Columns.Add("DT", System.Type.GetType("System.DateTime"))
        DataTable.Rows.Add("2019-08-27")

And See This Value in my table :
#11/18/2640 #
i don't know which section Change my Date Value . I be thankful if you solve my problem.

[kpmc]

And See This Value in my table

How are you seeing this value?

[Hamid.Khp]

with debug mode and stop program and see value in watch

[Hamid.Khp]

See This code please :

  
 DataTable.Columns.Add("DT", System.Type.GetType("System.DateTime"))
        DataTable.Rows.Add("2019-08-27")
        Dim DR() As DataRow
        DR = DataTable.Select("DT = #" + "2019-08-27" + "#")

the Dr.count = 0 ! ! !

[si_the_geek]

Welcome to VBForums

The Watch window (and the tools for most databases, as well as most other software) displays values using your regional settings, and you generally cannot do anything about that. In the Watch window you can alter the display by changing the value to use ToString, eg: MyDateValue.ToString("yyyy-MM-dd")

The important thing is that the value is correct, because that is all that gets saved.

The format is purely a display issue, so as long as your program displays/reads values correctly, everything is fine.

[Hamid.Khp]

Thank you for reply ,but i think the value is wrong in data table because i add above code (post 4 and post 5) and see wrong result.

[kpmc]

I was just going to say that you cant change the format of the date in the datatable because there is not such thing. This is a display instance derived from region.

In your statement you may instead want to try parameters using culture settings.

[Hamid.Khp]

can you explain the culture setting , what's your idea .thank's

[kpmc]

This is really uncharted waters for me, but try something like this (untested)

        Dim MyDate As DateTime = Nothing
        Date.TryParseExact("2019-08-27", "yyyy-MM-dd", Globalization.CultureInfo.CreateSpecificCulture("en-US"), Globalization.DateTimeStyles.None, MyDate)

        Using Cmd As New SqlCommand("Select * from tbl where datecol=@Mydate")
            Cmd.Parameters.AddWithValue("@Mydate", MyDate)
        End Using

This could be way off, or there could be a totally easier way... /shrug

[kpmc]

Ops, you wanted to return datarows

My eyes are getting bad of late. I think I need vac.

So without the command/params

 Dim MyDate As DateTime = Nothing
        Date.TryParseExact("2019-08-27", "yyyy-MM-dd", Globalization.CultureInfo.CreateSpecificCulture("en-US"), Globalization.DateTimeStyles.None, MyDate)

DR = DataTable.Select("DT = #" & MyDate  & "#")

[Hamid.Khp]

thank you very much , i use your method when i want to Write data and for search , it work very well for me .thanks

[Hamid.Khp]

After your hint ,my test code convert to this

  DataTable.Columns.Add("DT", System.Type.GetType("System.DateTime"))
        Dim MyDate As DateTime = Nothing
        Date.TryParseExact("2019-08-27", "yyyy-MM-dd", Globalization.CultureInfo.CreateSpecificCulture("en-US"), Globalization.DateTimeStyles.None, MyDate)
        DataTable.Rows.Add(MyDate)
        Dim DR() As DataRow
        Dim Sr As String = MyDate.ToShortDateString
        DR = DataTable.Select("DT = #" & Sr & "#")
  'SR = "05/06/1398"

But as you see problem convert to something else , this time the program see Date as gregorian and convert it to persian ! ! !
I realy don't know what happening. . .

[Hamid.Khp]

After your hint ,my test code convert to this

  DataTable.Columns.Add("DT", System.Type.GetType("System.DateTime"))
        Dim MyDate As DateTime = Nothing
        Date.TryParseExact("2019-08-27", "yyyy-MM-dd", Globalization.CultureInfo.CreateSpecificCulture("en-US"), Globalization.DateTimeStyles.None, MyDate)
        DataTable.Rows.Add(MyDate)
        Dim DR() As DataRow
        Dim Sr As String = MyDate.ToShortDateString
        DR = DataTable.Select("DT = #" & Sr & "#")
  'SR = "05/06/1398"

But as you see problem convert to something else , this time the program see Date as gregorian and convert it to persian ! ! !
I realy don't know what happening. . .

[si_the_geek]

Date.TryParseExact("2019-08-27", "yyyy-MM-dd", Globalization.CultureInfo.CreateSpecificCulture("en-US"), Globalization.DateTimeStyles.None, MyDate)

That line tries to store the value interpreted using US format (so that value will be in a few months time).

However, it is important to note that it tries to convert it. If for any reason it fails, there will not be an error - it will simply return False (and the variable value wont be set), but that currently isn't being checked.

This is how you could check it:

If Date.TryParseExact("2019-08-27", ..., MyDate) Then
  'your other code
Else
  'show a message to say it didn't convert
End If

Dim Sr As String = MyDate.ToShortDateString

That creates a string value which is formatted according to Regional Settings... which will be a different format to the one you started with.

[Hamid.Khp]

NO It Return True(After Check it) ,I really don't know what happening , first It don't Convert my date but after that my date convert automatically ,perhaps i should change my question like this :
What can i do if I want everybody with any region of windows don't see error in my program ?
thank's again.

[Hamid.Khp]

NO It Return True(After Check it) ,I really don't know what happening , first It don't Convert my date but after that my date convert automatically ,perhaps i should change my question like this :
What can i do if I want everybody with any region of windows don't see error in my program ?
thank's again.

[Hamid.Khp]

finaly it work
thanks everyone ,you give me idea to solve it ,for another persones :

        DataTable.Columns.Add("DT", System.Type.GetType("System.DateTime"))
        Dim MyDate As DateTime = Nothing
        Date.TryParseExact("2019-08-27", "yyyy-MM-dd", Globalization.CultureInfo.CreateSpecificCulture("en-US"), Globalization.DateTimeStyles.None, MyDate)
        DataTable.Rows.Add(MyDate)
        Dim DR() As DataRow
        Dim Sr As String = MyDate.ToString("yyyy-MM-dd", Globalization.CultureInfo.CreateSpecificCulture("en-US"))
        DR = DataTable.Select("DT = #" & Sr & "#")