Important! Clear A Datagrid

[aletheia]

Hi everyone, I have an easy question (but I'm going crazy!):

 

I do a query and I put data in a DataGrid; if I make another query on another table (WITH DIFFERENT COLUMNS NAMES) it shows me the columns of the 1st query, too!

How can I clear the STRUCTURE of the DataGrid?

 

Thank you very much :)

[aletheia]

Nodody use DataGrid here?

[Mothra]

Clearing a datagrid

 

Give this a try:

 

DataGrid1.DataSource = Nothing

[JABE]

I did a simple test; I just assigned the DataSource to the other datatable and the grid was correctly refreshed:

 

DataGrid1.DataSource = myDS.Tables("OtherTable")

[Mothra]

I guess that would be the quick route, huh?Guess it depends on how much you like to type! ;)

[aletheia]

No, no, it doesn't work anyway!!!

Here is my sub: what's wrong???

 

Private Sub btnVai_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnVai.Click

Try

ds.Clear()

ds.Dispose()

DataGrid1.DataSource = Nothing

cn.ConnectionString = cnString

cn.Open()

If txtQuery.SelectedText = "" Then

da.SelectCommand.CommandText = txtQuery.Text

Else

da.SelectCommand.CommandText = txtQuery.SelectedText

End If

da.Fill(ds, "Temp")

DataGrid1.DataSource = ds

DataGrid1.DataMember = "Temp"

lblRighe.Text = ds.Tables("Temp").Rows.Count & " righe selezionate"

Catch ex As OleDb.OleDbException

MsgBox("Istruzione SQL non valida", MsgBoxStyle.Critical, "Errore di sintassi SQL")

Finally

cn.Close()

cn.Dispose()

End Try

End Sub

[aletheia]

Pleaseee... help me... nobody seems to know...

 

Call Microsoft... call someone.... :eek:

[JABE]

Try specifying a different datatable name instead of using "Temp" for both queries.

[jfackler]

Alethia,

If a Data Table is created by a DataAdapter's .Fill or .FillSchema method, the Columns collection will be generated automatically.

Your DataTable "Temp" is persisting the column names try:

 

If txtQuery.SelectedText = "" Then
da.SelectCommand.CommandText = txtQuery.Text
Else
da.SelectCommand.CommandText = txtQuery.SelectedText  'my assumption is this if/else allows you to create the query you described

ds.Tables("Temp").Columns.Clear()  'this will clear the columns collection and with the da.Fill(ds, "Temp") call below, the "Temp" table column collection will be recreated.

End If
da.Fill(ds, "Temp")
DataGrid1.DataSource = ds
DataGrid1.DataMember = "Temp"
lblRighe.Text = ds.Tables("Temp").Rows.Count & " righe selezionate"
Catch ex As OleDb.OleDbException

 

 

Jon

[dynamic_sysop]

you need to specify the table , rather than just "Ds" i think . eg: 1 of my form's i can update the datagrid to show the table i wish like this :

DBAdapt.Fill(DBset, "UserTable")

DataGrid1.DataSource = DBset.Tables("UserTable")'/// update the datagrid to hold the new dataset.

hope this helps.

[aletheia]

Thanx to everyone, now it works. ;)

[jfackler]

Could you please post the code you used so future users can learn from this thread also?

 

Thanks,

 

Jon

[aletheia]

Jon, this sub works fine:

 

Private Sub btnVai_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnVai.Click

Try

ds.Clear()

ds.Dispose()

ds = New DataSet()

DataGrid1.DataSource = Nothing

DataGrid1.DataMember = Nothing

DataGrid1.SetDataBinding(Nothing, "")

cn.ConnectionString = cnString

cn.Open()

If txtQuery.SelectedText = "" Then

da.SelectCommand.CommandText = txtQuery.Text

Else

da.SelectCommand.CommandText = txtQuery.SelectedText

End If

da.Fill(ds, "Temp")

DataGrid1.DataSource = ds

DataGrid1.DataMember = "Temp"

lblRighe.Text = ds.Tables("Temp").Rows.Count & " righe selezionate"

Catch ex As OleDb.OleDbException

MsgBox("Istruzione SQL non valida", MsgBoxStyle.Critical, "Errore di sintassi SQL")

Finally

cn.Close()

cn.Dispose()

End Try

End Sub

[DayWalker]

Try this its quicker. If you filling the datagrid via a dataset.

If ds.tables.contains("TableName") then ds.tables.clear()

Dunno might be out of my league here