DbConcurrency - Design Problem

[Agnes]

I had solve the DbConcurrency problem by using Try and catch , and compare
the Original & Currenct Record.
For the single table, I can use the above approcah sucesfully.
However, for one-to-many relationship,. I don't know how to do it.
For, example, Invoice (Two tables involved, invoice_info & Invoice_chg) ,
If two users amend one item's description in Invoice , I don't know how to
check the sub-item.
**I only know how to pass one table with one primary key to check the
DBconcurrency


_daBase.Fill(_d sBase_ver, _dtTable)
Dim _col() As DataColumn =
{_dsBase_ver.Ta bles(_dtTable). Columns(_colnam e)}
_dsBase_ver.Tab les(_dtTable).P rimaryKey = _col
rowInDB = _dsBase_ver.Tab les(_dtTable).R ows.Find(_searc hkey)

' Loop through the column values.
Dim i As Integer
Dim strData_o, strData_c As String
For i = 0 To dbcx.Row.ItemAr ray.Length - 1
strData_o = dbcx.Row(i, DataRowVersion. Original).ToStr ing
strData_c = rowInDB(i, DataRowVersion. Current).ToStri ng
If strData_o <> strData_c Then

strOriginal &= dbcx.Row(i, DataRowVersion. Original) &
ControlChars.Ta b
strCurrent &= rowInDB(i, DataRowVersion. Current) &
ControlChars.Ta b
strYour &= dbcx.Row(i, DataRowVersion. Current) &
ControlChars.Ta b
End If
Next