3rd Tier data not displaying in Data Adapter Preview

dotnet framework


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    Hello everybody, The MSDN says about ShowDialog that "When a form is displayed as a modal dialog box, clicking the Close button (the button with an X at the upper-right corner of the form) causes the form to be hidden and the DialogResult property to be set to DialogResult.Cancel. Unlike modeless forms, the Close method is not called by the .NET Framework when the user clicks the close form button of a dialog box or sets the value of the DialogResult property. Instead the form is hidden and can be shown again without creating a new instance of the dialog box. Because a form displayed as a dialog box is not closed, you must call the Dispose method of the form when the form is no longer needed by your application." The way I understand this is that even if I re-instantiate the class that implements my form, the framework will reuse some previously created structures and that's how I would explain why the Load event is not fired for subsequent calls to ShowDialog. So here is my question: What is the pattern I need to use to display one form over and over and make sure that all internal controls are initialized to proper values every time the form is shown? What is the event that's fired every time ShowDialog is called, if there is such an event? If not, how else should I approach this? TIA, Eddie
  • 2. Insert row in datagridview
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3rd Tier data not displaying in Data Adapter Preview

Postby V2hpc2t5Um9tZW8 » Wed, 22 Jun 2005 04:49:05 GMT

I have a dataset consisting of 3 tables:  tableA is the parent of tblB who is 
the parent of tblC.  They each have a SQL data adapter that fills them with 
the correct data.  However, I cannot get the data from tblC to display in the 
ultrawingrid.  For reasons I explain in the 3rd para. below, this appears not 
to be an issue with the grid.

In design the grid shows each band correctly.  When I run the form and fill 
the grid, I get no complaint of failing to enable the constraints.  Bands 0 & 
1 show data but Band 2 does not.

When I preview the data using the data adapters, I fill each data table in 
the correct order, and, again, I get no errors and the data in tableC shows 
up.  In the Data tables list of the Data Adapter Preview window, I can click 
on each table and see the data in them.  An alternate way to view the data in 
child tables, is to click on the + in each row of the parent table which will 
show the relationship link.  Clicking on the link shows the related rows in 
the child table.  This work fine for tableA; however, for tableB clicking on 
the link shows no rows from tableC even though clicking on tableC shows 
there is data there.

(PkgID is the PK of tableA)

(PkgID, MktName, ProdLab, ProdSTD is PK of tableB)
(the relationship from tableA to tableB is PkgID (PK) PkgID (FK))

(PkgID, MktName, ProdLab, ProdSTD, ModID is PK of tableC)
(for the relationship between tableB and tableC -- each of the 1st four 
columns are mapped to the corresponding column in tableC)

For each relationship, reate foreign key constraint onlyis not checked 
and all the values for the rules are set to default.

Here are examples of actual data in order of tableA, tableB, tableC:

PkgID  -- PkgName 

PkgID MktName ProdLab rodSTD Qty DivideQty 
95 GRAD 5x7 20 2 1 

PkgID MktName ProdLab rodSTD ModID
95-GRAD- 5x7-20-BW

If anyone sees any problem with this, your help is appreciated.


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4.Data Adapters, Data Sets, Data TableMappings, and XML

Here's what I'm trying to do:

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3. Create a dataset

3. Read in a schema using dataset.ReadXmLSchema

4. Read in an xml file that contains the data using 
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5. Add 3 new columns to the dataset. (These columns have 
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7. Modify some data in the other columns using xpath 
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Everything seems to work fine until step 8. I get all the 
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Run-time exception thrown : 
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columns from the table once the DataSet is mapped to a 
loaded XML document.

Any ideas about how I can either fix this or do it another 


5.problem with data adapter and data set while inserting and retrieving data

i am using a data adapter and a dataset for filling and retrieving data
into .mdb database.
following is the code.....

for the form load event
  Dim dc(0) As DataColumn
            If OleDbConnection1.State = ConnectionState.Closed Then
                MsgBox("connection can not be established")
            End If
            DA.Fill(DataSet11, "Table1")
            cmd = New OleDbCommandBuilder(DA)
            dc(0) = DataSet11.Tables("Table1").Columns("EmpID")
            DataSet11.Tables("Table1").PrimaryKey = dc
        Catch ex As Exception
        End Try
        Delete.Enabled = False
    End Sub

for  inserting values into the DB

Private Sub Insert_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Insert.Click
        Dim dr As DataRow
        dr = DataSet11.Tables("Table1").NewRow
        dr.Item(0) = Val(TB1.Text)
        dr.Item(1) = TB2.Text
        dr.Item(2) = TB3.Text
        dr.Item(3) = Val(TB4.Text)
        dr.Item(4) = TB5.Text
        DA.Update(DataSet11, "Table1")
        MsgBox("data is saved")
        rno = 0
        call filldata()

filldata function consists of the following

 With DataSet11.Tables("Table1").Rows(rno)
         TB1.Text = Trim(.Item(0))
         TB2.Text = Trim(.Item(1))
         TB3.Text = Trim(.Item(2))
         TB5.Text = Trim(.Item(4))
         End With

the error it gives is " there is no row at
0........system.nullreference...........i checked the connection and
its working fine and also the database is getting accessed........the
error is occuring at the line " With
DataSet11.Tables("Table1").Rows(rno) "

6. datagrid not displaying data table data

7. Data->Generate Dataset|Preview Data

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