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Datarelation causing odd result

Posted on 2007-03-29
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Last Modified: 2008-02-01
I am getting odd results which I suspect is related to a datarelation problem.
 I am trying to get the longitude and latitude for various postcodes which are supplied in customer addresses. The results i get are all rather odd with the location for the Birmingham postcode being in Scotland!
I think this is related to the constraints in the datarelationship I set up particularly as when i set enableFocre Constraints to true it generates a fault (and not if set to false)- "This constraint cannot be enabled as not all values have corresponding parent values."
Any ideas

Seb
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Question by:sebastiz
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3 Comments
 

Author Comment

by:sebastiz
ID: 18819648
Sorry.... This is the code:


Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.Odbc
Imports System.Data.sql

Imports System.Data.OleDb

Partial Class NHSmap3
    Inherits System.Web.UI.Page
    Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim connectionstring As String = "DATABASE=blabla;DESCRIPTION=blabla;DSN=blabla;OPTION=0;PORT=0;SERVER=xxxxxxx;UID=sebo27"
        Dim querystring As String = "SELECT blabla.`User`.UserName as USER, blabla.`User`.Postcode AS pcode_orig, LEFT(blabla.`User`.Postcode, LENGTH(blabla.`User`.Postcode) - LOCATE(' ', REVERSE(blabla.`User`.Postcode))) as pcode,blabla.`User`.Tel, blabla.`User`.Email, blabla.`User`.Address AS Address, blabla.Customer.CustomerID FROM blabla.Customer, blabla.`User` WHERE blabla.Customer.UserID = blabla.`User`.UserID AND blabla.`User`.Postcode IS NOT NULL"


        Dim connection As New OdbcConnection(connectionstring)
        Dim dcom As New OdbcCommand(querystring, connection)
        connection.Open()
        Dim dbr As OdbcDataReader = dcom.ExecuteReader()
        Dim dt As New Data.DataTable("Table")
        Dim ds As New DataSet
        'ds.EnforceConstraints = False

        ds.Tables.Add(dt)


        dt.Load(dbr)
        dbr.Close()
       



        Dim dv As New DataView
        dv.Table = dt
        dv.Sort = "pcode"

       

        'Use the Access database to translate postcodes into longitudes and latitudes

        Dim conn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Documents and Settings\Administrator\Desktop\UKPostcodes.mdb;Persist Security Info=False"

        Dim cmd As String = "SELECT postcode AS pcode, latitude, longitude FROM [uk-postcodes]"


        Dim conn1 As New OleDbConnection(conn)
        Dim dcom1 As New OleDbCommand(cmd, conn1)
        conn1.Open()
        Dim dbr1 As OleDbDataReader = dcom1.ExecuteReader()
        Dim dt1 As New Data.DataTable("Table1")

        dt1.Load(dbr1)
        conn1.Close()



        ds.Tables.Add(dt1)
        ds.EnforceConstraints = False


        Dim dre As New DataRelation("Connectpcodes", _
        ds.Tables("Table").Columns("pcode"), _
        ds.Tables("Table1").Columns("pcode"))
        Dim dv1 As New DataView
        ds.Relations.Add(dre)






        'Display the Category and Child Products Within
        Dim dtrParent As DataRow
        Dim dtrChild As DataRow
        Dim dt2 As New DataTable("Merge")
        Dim dc2 As New DataColumn("USER")
        Dim dc3 As New DataColumn("pcode")
        Dim dc4 As New DataColumn("longitude")
        Dim dc5 As New DataColumn("latitude")
        dt2.Columns.Add(dc2)
        dt2.Columns.Add(dc3)
        dt2.Columns.Add(dc4)


        For Each dtrParent In ds.Tables("Table").Rows
            lblDisplay.Text &= "<h3>" & dtrParent("pcode") & dtrParent("USER") & " </h3><ul>"
            For Each dtrChild In dtrParent.GetChildRows(dre)
                lblDisplay.Text &= "<li>" & dtrChild("pcode") & dtrChild("latitude") & "</li>"
            Next
            lblDisplay.Text &= "</ul>"
        Next


       
        Dim i As Integer
       

        For Each dtrParent In ds.Tables("Table").Rows

            For i = 1 To 3


                dt2.Rows().Add(dtrParent("USER"), dtrParent("pcode"), dtrChild("longitude"))
               
               

               


            Next i
        Next
    End Sub
End Class

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Author Comment

by:sebastiz
ID: 18869955
Ive sorted this- it was related to the for each statement and the fact the dtrChild was being used before it was defined. Can I get the points refunded?

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Accepted Solution

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EE_AutoDeleter earned 0 total points
ID: 18962744
sebastiz,
Because you have presented a solution to your own problem which may be helpful to future searches, this question is now PAQed and your points have been refunded.

EE_AutoDeleter
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