Ich versuche, ein Meldungsfeld anzuzeigen, wenn keine Daten aus der Datenbank am Ende des VergleichsWie ein Meldungsfeld i angezeigt, wenn die Textbox nach einer Suche leer
Private Sub submitbutton_Click(sender As Object,
e As EventArgs) Handles submitbutton.Click myConnection.Open()
tutorboxr.Clear()
compboxr.Clear()
Dim str As String
Dim etr As String
str="SELECT * FROM 2014Results WHERE (Competitor = '" & Competitor.Text &"')"
etr="SELECT * FROM 2014Results WHERE (Event = '" & EventBox.Text &"')"
Dim cmd As OleDbCommand=New OleDbCommand(str,
myConnection)
Dim emd As OleDbCommand=New OleDbCommand(etr,
myConnection) dr=cmd.ExecuteReader
While dr.Read()
compboxr.Text=dr("Rank").ToString
textbox.Text=dr("Reg").ToString
If Competitor.Text="" Then MessageBox.Show("This student wasn't a ranking placeholder!",
MessageBoxButtons.OK,
MessageBoxIcon.Error)
End If
End While myConnection.Close()
If Competitor.Text="" Then MessageBox.Show("Please enter a students name",
"No entry",
MessageBoxButtons.OK,
MessageBoxIcon.Error) With Competitor .Focus() .SelectAll() End With Exit Sub
End If
End Sub
erhalte ich diesen Fehler:
Overload resolution failed because no accessible 'Show' can be called without a narrowing conversion: : Argument matching parameter narrows from 'MessageBoxButtons' to 'String'. : Argument matching parameter narrows from to 'MessageBoxButtons'. : Argument matching parameter narrows from 'String' to. : Argument matching parameter 'text' narrows from 'MessageBoxButtons' to 'String'. : Argument matching parameter narrows from to 'String'.
Schalten Option streng auf –