Table doesn't update - What am I doing wrong?



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Table doesn't update - What am I doing wrong?

Postby Gary Paris » Mon, 18 Apr 2005 05:12:28 GMT

I have a form that has three textboxes on.  I want to be able to modify the 
FirstName, LastName, and Address

Here is the code to load the data
   Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load

        Dim strSQL As String = "Select * from Contact where sysid = '" & 
g_sysID & "'"
        DB = New SqlClient.SqlDataAdapter(strSQL, CN)
        DB.Fill(ES, "Contact")

        If ES.Tables("Contact").Rows.Count > 0 Then
            txtAddress.Text = 
            txtFirst_Name.Text = 
            txtLast_Name.Text = 
        End If

    End Sub
Here is the code to update the table
   Private Sub btnUpdate_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles btnUpdate.Click

            es.Tables(0).Rows(0).Item("First_Name") = txtFirst_Name.Text
            es.Tables(0).Rows(0).Item("Last_Name") = txtLast_Name.Text
            es.Tables(0).Rows(0).Item("con1_02_03") = txtAddress.Text
            DB.Update(ES, "Contact")

        Catch ex As Exception


        End Try

    End Sub
Why doesn't the table update?  Can anyone give me an explanation and also if 
I need to change code, please tell me where to put the modifications?



RE: Table doesn't update - What am I doing wrong?

Postby Q2hhcmxpZQ » Mon, 18 Apr 2005 05:35:01 GMT

You should start the update routine by making a call to MyDataRow.BeginUpdate
Then add the lines that create the changes, followed by 

If you look at the fourth implementation of DataRow, you will see a second 
parameter called DataRowVersion.  The last item in that enum is Proposed.

(You can create and step through some code to test the values of the various 
DataRowVersions to see exactly what is happening.)

When you first make the change, the value is changed only for "Proposed".
When you call AcceptChanges, the Proposed value becomes the "Current" value.

When complete, call MyDataRow.EndEdit.

Of course, this only affects the DataTable, not the database.  Changes to 
the database will only be happen when you execute an UPDATE statement.

Re: Table doesn't update - What am I doing wrong?

Postby Gary Paris » Mon, 18 Apr 2005 05:49:58 GMT

i Charlie,

Thanks for the reply but I don't understand a few things. Where do I put
MyDataRow.BeginUpdate? I don't have a MyDataRow defined. Do I need to
specifically define a datarow?

What does "the fourth implementation of DataRow" mean? I have no idea.

Sorry but I am a beginner and need more explicit guidance. If you could put
the changes into my code that would help lots.



"Charlie" <cfarrier at> wrote in message
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RE: Table doesn't update - What am I doing wrong?

Postby Q2hhcmxpZQ » Mon, 18 Apr 2005 05:51:08 GMT

Your DataAdapter.Update command needs to have an UpdateCommand property set 
for DataAdapter.Update to execute.

I find it easier and more straightforward to just concatenate the UPDATE 
statement in code, assign it to a new command, and execute the Command with 

Re: Table doesn't update - What am I doing wrong?

Postby Gary Paris » Mon, 18 Apr 2005 05:55:56 GMT

Can you give me an example of how to do that?



RE: Table doesn't update - What am I doing wrong?

Postby Q2hhcmxpZQ » Mon, 18 Apr 2005 05:56:02 GMT

Also, when you put together the UPDATE statement, be sure to include the 
WHERE clause.  Otherwise, you will update every record, and essentially 
destroy your data.  I don't want to insult your intelligence, but it's an 
easy mistake to make, and worth noting.

Re: Table doesn't update - What am I doing wrong?

Postby Q2hhcmxpZQ » Mon, 18 Apr 2005 05:59:01 GMT

yDataRow just means the datarow you are using:

When you see My used this way, it just means "your instance", as opposed to
a shared member of an object, such as String.Join...

"Gary Paris" wrote:

Re: Table doesn't update - What am I doing wrong?

Postby Q2hhcmxpZQ » Mon, 18 Apr 2005 06:08:04 GMT

ou could adapt this. You can get the exact syntax of the UPDATE statement
through various sites, in case I have a typo here...

Dim UPDATE As String = "UPDATE MyTable SET FirstName = '" &
txtFirstName.text & "' LastName = " & txtLastName.text & " WHERE PrimaryKey =
Dim CMD As New OleDb.OleDbCommand(UPDATE, MyConnection)

"Gary Paris" wrote:

Re: Table doesn't update - What am I doing wrong?

Postby Cor Ligthert » Mon, 18 Apr 2005 17:07:44 GMT


There are at least two things what makes that your update does not work.
You are have no commands in your dataadapter.
You use the acceptchanges wrong.

I have made some corrections typed (so watch typos) inline in this message 
so look below to them.

You better create and dispose better as well the connection in those 
procedures because now you don't free the connectionpool.

dim cb as new sqlclient.sqlcommandbuilder(db)

delete the row above, this means that all rowstates which are set to a 
changed state will be set to unchanged and the changes are accepted, so the 
dataadapter has nothing to change. It is implicitly done by the dataadapter 
when a change is done.

I hope this helps,


Re: Table doesn't update - What am I doing wrong?

Postby Robert Payne » Tue, 19 Apr 2005 00:53:09 GMT


When you execute the Update method for the DataAdapter, it checks the 
RowStatus of each DataRow in the DataSet to determine whether to execute the 
Insert, Update, or Delete command.  Executing the AcceptChanges method on 
the DataSet resets the RowState property of all rows to Unchanged, thereby, 
making the rows appear as if they've never been modified.  Remove the 
AcceptChanges line and your database should be updated as expected.


Similar Threads:

1.What am I doing wrong - Trying to update

I have enclosed the sample code that I created.  I want to read in employee 
data, and modify a few fields.  I have tried to globally declare the objects 
that I need but I still am having problems.  I want to update in a seperate 
subroutine and seem to have problems.  HELP please.

Public Class Form1

    Inherits System.Windows.Forms.Form
    Public cn As OleDb.OleDbConnection
    Public ds As DataSet
    Public da As OleDb.OleDbDataAdapter
    Public rowEmployee As DataRow

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load

            Dim strConn As String
            strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data 

            Dim cn As New OleDb.OleDbConnection(strConn)

            Dim strSQL As String
            strSQL = "SELECT EmployeeID, FirstName, LastName, Address, City, 
Region, " & _
                "PostalCode from Employees ORDER BY LastName, FirstName"

            Dim da = New OleDb.OleDbDataAdapter(strSQL, strConn)
            Dim ds As New DataSet

            da.Fill(ds, "Employees")

            Dim tbl As DataTable = ds.Tables(0)

            'rowEmployee = New DataRow
            rowEmployee = tbl.Rows(0)
            txtFirstName.Text = rowEmployee("FirstName")
            txtLastName.Text = rowEmployee("LastName")
            txtAddress.Text = rowEmployee("Address")

        Catch ex As Exception
            MessageBox.Show(ex.Message & " :: " & ex.Source)
        End Try
    End Sub

    Private Sub btnUpdate_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles btnUpdate.Click
            rowEmployee("LastName") = txtLastName.Text

        Catch ex As Exception

            MessageBox.Show(ex.Message & " :: " & ex.Source)

        End Try

    End Sub
End Class

When it runs I get the following error:

"Object reference not set to an instance of an object."

on the             da.Update(ds)       line in the btnUpdate_Click routine.




2.What am I doing wrong??

Here is what I am trying:

\Application Data", _
"C:\Documents and Settings\" & Environment.UserName & "\Application
Data\Adobe", True)
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\Local Settings", _
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\Application Data\Adobe", True)
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I get the error that: \\server\all\sets\Application Data  is not
found, but it is there, and inside that folder I want to copy a folder
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Also, will this work like this, one statement after another to do two


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Cany anyone advise what I'm doing wrong please? The fact that the file
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Regards - One Handed Man

Author : Fish .NET & Keep .NET
This posting is provided "AS IS" with no warranties,
and confers no rights.

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