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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
 
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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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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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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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