พี่ครับผม error conversion from string "select * from staff " to type interget not valid

Imports System.Data
Imports System.Data.OleDb
Imports System.Configuration
Public Class database
    Private con As OleDbConnection
    Private cmd As OleDbCommand
    Private strconstring As String

    Public Sub New()
        strconstring = System.Configuration.ConfigurationManager.ConnectionStrings("Chase.My.MySettings.chaseConnectionString").ConnectionString
    End Sub

    Public Function querydataset(ByVal strsql As String) As DataSet
        Dim ds As DataSet
        Dim da As New OleDbDataAdapter
        con = New OleDbConnection
        With con
            .ConnectionString = strconstring
            .Open()
        End With
        cmd = New OleDbCommand
        With cmd
            .Connection = con
            .CommandType = strsql
            .CommandType = CommandType.Text
        End With
        da.SelectCommand = cmd
        da.Fill(ds)
        Return ds
    End Function

    Public Function queryexecute(ByVal strsql As String) As Boolean
        con = New OleDbConnection
        With con
            .ConnectionString = strconstring
            .Open()
        End With
        Try
            cmd = New OleDbCommand
            With cmd
                .Connection = con
                .CommandType = CommandType.Text
                .CommandText = strsql
            End With
            cmd.ExecuteNonQuery()
            Return True
        Catch ex As Exception
            Return False
        End Try
    End Function

End Class

Imports System.Data
Imports System.Data.OleDb
Public Class Form5

    Dim clsdb As New database 

    Private Sub Form5_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Call mydataset()

    End Sub

    Sub mydataset()
        Dim strsql As String = "select * from staff "
        Dim ds As DataSet
        ds = clsdb.querydataset(strsql)
        Me.DataGrid1.DataSource = ds.Tables(0)
    End Sub
End Class