Dim dbase As String() = New String() {"d1", "d2", "d3"}
Dim mycon As New OleDbConnection()
Dim myadapt As New OleDbDataAdapter()
Dim mytable As New DataTable()
Dim myset As DataSet
For i = 0 To 2
Dim constr As String = "provider=access provider; AttachDbFileName=|DataDirectory|\" & dbase(i)
mycon = New OleDbConnection(constr)
myadapt = New OleDbDataAdapter("select * from t1,t2,t3 .....", mycon)
mycon.Open()
myset = New DataSet()
myadapt.Fill(myset)
mycon.Close()
For j = 0 To myset.Tables.Count - 1
For h = 0 To myset.Tables(j).Rows.Count - 1
If (myset.Tables(j).Rows(h)("اسم الحقل الذي تريد البحث فيه") = "sajad") Then
''' عرض البيانات
End If
Next
Next
Next