Private ds As New DataSet
    Private dt1 As DataTable
    Private dt2 As DataTable
    Private dt3 As DataTable
    Private dtJoinGrid As DataTable
 
    Private da1 As System.Data.SqlClient.SqlDataAdapter
    Private da2 As System.Data.SqlClient.SqlDataAdapter
    Private da3 As System.Data.SqlClient.SqlDataAdapter
 
    Dim sql As String
    dt3 = New DataTable("Impfstoff")
    sql = "SELECT Bezeichnung, Nr FROM Impfstoff"
    da3 = New SqlClient.SqlDataAdapter(sql, sqlcn)
    da3.Fill(dt3)
    ds.Tables.Add(dt3)
    ' // usw.