Read the file into an array of bytes and INSERT it to the DB. The DB can allocate a ID number automatically (Google for IDENTITY columns) and that can provide your "number" for searching.
Dim bytes As Byte() = File.ReadAllBytes(pathToFile)
Using con As SqlConnection = New SqlConnection(strConnect)
con.Open()
Using cmd As SqlCommand = New SqlCommand("INSERT INTO MyTable (PDFDate) VALUES (@BD)", con)
cmd.Parameters.AddWithValue("@BD", bytes)
cmd.ExecuteNonQuery()
End Using
End Using