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VB.NET INSERT ERROR - Conversion failed when converting datetime from character string

Posted on 2009-05-11
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Last Modified: 2012-05-06
I am having issue with inserting some value from a textbox into SQL database from a windows form application.  Basically I have 2 textboxes that are use for Start/End Time.  So 6:00 or 14:00 will be the input data.  When I try to insert that, I get the following error.  Any ideas on what I need to do to these textboxes?

"Conversion failed when converting datetime from character string."

Below is my query:

CMD.COMMANDTEXT = "INSERT INTO EMP_TIME VALUES(" & strID & ", " & _

                                     "'" & txtStart.Text & "', '" & txtEnd.Text & "')"

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Question by:holemania
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8 Comments
 
LVL 15

Expert Comment

by:mohan_sekar
ID: 24358378
assuming you've a valid date value in the text field, use CDate(txtStart.Text)
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LVL 8

Expert Comment

by:Bob Hoffman
ID: 24358415
Just the time value won't cast to a date. You have two choices:
1. Change your date fields in the Db to varchars
2. Load you time value as follows '1900-01-01' 06:00:00.000'
 
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Author Comment

by:holemania
ID: 24359068
Yes it is just the time alone.  Is there anyway I can check to make sure it's in time format or way of automatically formatting it into time?  If that can be done, then I can also change the date field into varchars?

Example if someone enter 6:00 or 600 should be formated as 6:00?  If someone put in 123ABC, it would error out or give message that it needs to be in time format?
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LVL 8

Accepted Solution

by:
Bob Hoffman earned 400 total points
ID: 24359307
If your using your time values later in your SQL to test against ie(Start less the End, etc) I would leave them as date fields. You could use the IsTime function I supplied to check for a valid time. If your just storing the time to display ot print later store it as varchar(5) and use the TimeMask sub and the KeyPress and LostFocus events to make sure the time is valid.
   Private Function IsTime(ByVal strTime As String) As Boolean

        Try

            If IsDate("1900-01-01 " & strTime.Trim()) Then Return True

            Return False

        Catch ex As Exception

            Return False

        End Try
 

    Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress

        Call TimeMask(TextBox1.Text, Asc(e.KeyChar))

    End Sub
 

    Private Sub TextBox1_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.LostFocus

        'Edit date

        If Trim$(TextBox1.Text) <> "" Then

            If Not IsDate(TextBox1.Text) Then

                MsgBox("Time is invalid.", vbOKOnly, "Error message")

                TextBox1.Focus()

            Else

                TextBox1.Text = Format(TextBox1.Text, "hh:mm")

            End If

        End If

    End Sub
 

    Public Sub TimeMask(ByVal strTime As String, ByVal KeyAscii As Integer)
 

        'Allow these keys

        If (KeyAscii = System.Windows.Forms.Keys.Back) _

         Or KeyAscii = System.Windows.Forms.Keys.Space _

         Or KeyAscii = System.Windows.Forms.Keys.Left _

         Or KeyAscii = System.Windows.Forms.Keys.Right _

         Or KeyAscii = System.Windows.Forms.Keys.Delete Then

            Exit Sub

        End If
 

        'Only Allow ":" in positions 3

        If KeyAscii = 58 Then

            If Len(strTime) <> 2 Then

                KeyAscii = 0

                Exit Sub

            End If

        End If
 

        'Only allow numbers and  ":"

        If (KeyAscii < 48 Or KeyAscii > 58) Then

            KeyAscii = 0

            Exit Sub

        End If
 

        ' Send ":"

        If Len(strTime) = 1 Then

            System.Windows.Forms.SendKeys.Send(":")

        End If
 

    End Sub

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Expert Comment

by:Bob Hoffman
ID: 24359336
use this lostfocus handle not the one above.
    Private Sub TextBox1_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.LostFocus

        'Edit date

        If Trim$(TextBox1.Text) <> "" Then

            If Not IsDate(TextBox1.Text) Then

                MsgBox("Time is invalid.", vbOKOnly, "Error message")

                TextBox1.Focus()

            Else

                TextBox1.Text = Format(CDate(TextBox1.Text), "HH:mm")

            End If

        End If

    End Sub

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LVL 15

Expert Comment

by:JackOfPH
ID: 24360497
My Suggestion to you.

1) Change the datatype of the field in your database to DateTime.
2) Then in storing the value, use the function I posted below to check if you have a valid time before saving it.
Private Function IsValidTime(ByVal Time As String) As Boolean

        Return DateTime.TryParse(Time, New DateTime)

End Function

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Assisted Solution

by:JackOfPH
JackOfPH earned 100 total points
ID: 24360500
And here is an example on how you can use it.

Private Sub TextBox1_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles TextBox1.Validating

        If IsValidTime(Me.TextBox1.Text) = False Then

            MessageBox.Show("Invalid time entered.")

            e.Cancel = True

        End If

End Sub

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Author Closing Comment

by:holemania
ID: 31580301
Thanks.  That worked well.
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