How do I create a dataset in VB.NET from this code? - vb.net

Question

I currently have the following code in my project which populates a DataGridView object with the results of an SQL query.
Sub PerformQuery(ByVal SQLText As String)
Dim DbConnection As New OleDb.OleDbConnection(createConnectionString)
Dim SQLQuery As String = SQLText
Dim Adapter As New OleDb.OleDbDataAdapter(SQLQuery, DbConnection)
Try
Using Table As New DataTable
Adapter.Fill(Table)
Table.Locale = Globalization.CultureInfo.InvariantCulture
DbConnection.Close()
DataGridView1.DataSource = Table
End Using
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
Elsewhere in my project I can create a DataSet object using the code
Dim ds As New DataSet
And then extract data from it using code like:
MaxRows = ds.Tables("Dataset_Users").Rows.Count
Rather than populating a DataGridView, how can I use the PerformQuery code to create a dataset?
Thank you in advance for your help.

Answer 1

I think you are after the following:
Try
Dim ds As New DataSet
Using Table As New DataTable
Adapter.Fill(Table)
Table.Locale = Globalization.CultureInfo.InvariantCulture
DbConnection.Close()
DataGridView1.DataSource = Table
ds.Table.Add(Table)
End Using
Catch ex As Exception
MsgBox(ex.Message)
End Try
Or as in your example you was after the Number of rows in the dataset you can do the same with the DataTable, For Example:
Try
Dim MaxRows As Integer
Using Table As New DataTable
Adapter.Fill(Table)
Table.Locale = Globalization.CultureInfo.InvariantCulture
DbConnection.Close()
DataGridView1.DataSource = Table
'' Getting the number of rows in the DataTable
MaxRows = Table.Rows.Count
End Using
Catch ex As Exception
MsgBox(ex.Message)
End Try

Answer 2

Think in a more functional style. Return the table instead of setting to grid. While we're here, let's update the method so you don't have to write queries anymore that leave you wide open to sql injection attacks:
Function PerformQuery(ByVal SQLText As String, ByVal ParamArray Parameters() As OleDbParameter) As DataTable
Dim result As New DataTable()
Using cn As New OleDb.OleDbConnection(createConnectionString), _
cmd As New OleDb.OleDbCommand(SQLText, cn), _
Adapter As New OleDb.OleDbDataAdapter(cmd, cn)
If Parameters IsNot Nothing AndAlso Parameters.Length > 0 Then
cmd.Parameters.AddRange(Parameters)
End If
Adapter.Fill(result)
End Using
Return Result
End Function
Note that I also removed the error handling and locale code. You still need to do that stuff, but when you want to just return a datatable instead of interact directly with the user interface in a method you have effectively moved your code to a lower level of abstraction. When you do that, you probably don't want to deal with the error handling at this lower level any more; instead let the exceptions bubble up where you can handle them closer to the user interface.
Now you call the updated method like this:
Dim sql As String = "SELECT * FROM Customers WHERE CustomerID = ?"
Dim CustID As New OleDb.OleDbParameter("CustomerId", OleDbType.Integer)
CustID.Value = 123456
Try
DataGridView1.DataSource = PerformQuery(sql, CustID)
Catch Ex As Excpetion
MsgBox(Ex.Message)
End Try