Best way to merge two Datatables - vb.net

Question

I need to marge two datatables with condition. I have a datatable where the data comes from a local XML Database and another datatable where the data comes from a remote SQL Server.
If any update made in the remote datatable I need to update/merge with the local datatable. Here is what I have so far:
Public Sub MargeTwoTable()
Dim SQL As String = ""
Dim RemoteTable As New DataTable
Dim LocalTable As DataTable
Dim dal As New DalComon
Dim yy As Integer = 0
Dim UpdateDate As String
Dim TableName As String = "V_Book_Price"
LocalTable = LoadDataTable(TableName, True)
UpdateDate = LocalTable.Compute("MAX(update_date)", Nothing)
SQL = "select * from V_Book_Price where Update_Date > '" & UpdateDate & "'"
RemoteTable = dal.GetDataSetBySQL(SQL).Tables(0)
If RemoteTable.Rows.Count > 0 Then
For i = 0 To RemoteTable.Rows.Count - 1
Dim st As DataRow
Dim mm() As DataRow = LocalTable.Select("ID = '" & RemoteTable.Rows(i).Item("ID") & "'")
If mm.Length = 0 Then
st = LocalTable.NewRow
For yy = 0 To RemoteTable.Columns.Count - 1
st(yy) = RemoteTable.Rows(i)(yy)
Next
LocalTable.Rows.Add(st)
Else
st = mm(0)
For yy = 0 To RemoteTable.Columns.Count - 1
If IsDate(RemoteTable.Rows(i)(yy)) Then
st(yy) = CDate(RemoteTable.Rows(i)(yy)).ToString("s")
Else
st(yy) = RemoteTable.Rows(i)(yy)
End If
Next
mm = Nothing
End If
Next
End If
End Sub
In this code data comes from the remote database which updates a date getter then the local database . Both tables have "ID" as the primary key. The code is working well, but the problem is that when more than 1000 records are updated this function takes too long using loops.

Answer 1

Not sure if can be applicable, but have you ever looked at the
DataTable.LoadDataRow() method?.
It seems a good candidate to substitute all of you code above.
Your code could be simplified to these lines
Dim row as DataRow
For Each row in RemoteTable.Rows
LocalTable.LoadDataRow(row.ItemArray, false)
Next
Another alternative could be the DataTable.Merge that could cut your code to a single line
LocalTable.Merge(RemoteTable, False)
However, the real effectiveness of these two methods depends on the schema compatibility and from the presence of AutoNumber (identity) columns.