VB .NET - DB Update [Archive]

Hecate

09-13-02, 05:23

Hello,

I am new in VB .NET world and I am blocked by a little problem when trying to update a DB record.

It seems I can't find the right way to implement a Data Adtaper and Data Set derived from a master class.
The Data access occurs correctly, I can browse my records, but when trying to perform an update or an insert, I receive an exception fault:
Null value not allowed.

It seems the link isn't done correctly between my field in the form and my derivde DataSet.

Does anyone have an exemple how it has to be programmed?

Thanks in advance.

Hecate.

rnealejr

09-13-02, 23:43

What are you trying to insert/update ? Post the data definition of the table you are trying to insert/update. Be as specific as possible as to what you are updating/inserting in your code and the actual definition of the table ?

Sef

09-14-02, 06:17

Take another look at the structure of your table which you are trying to update.
There must be a field that you have set not to allow null values. As in, it should have data inserted into it on every instance of populating the table.
While at the front end, no data has been availed for this field.

The only sure test is to first make sure that you insert something for every field in the table.

Hecate

09-16-02, 04:37

The definition of my table is quiet easy:

Id - Int - 4 - Null NOT allowed
Desc1 - Varchar - 100 - Null Allowed
Desc2 - Varchar - 100 - Null Allowed

And here is the code:
1) Update command:

Private Sub cmdUpd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdUpd.Click
Dim con As New ds_vehicle

Me.BindingContext(loc_ds_vehicle, "cat_veh").EndCurrentEdit()
ds = CType(loc_ds_vehicle.GetChanges, CSF.ds_vehicle)
con.UpdateDataSource(ds)
loc_ds_vehicle.Merge(ds)
loc_ds_vehicle.AcceptChanges()
End Sub

2) DataAdapter Update defined in another module:

Public Sub UpdateDataSource(ByVal ds As CSF.ds_vehicle)
DbConnection.Open()

Dim UpdatedRows As System.Data.DataSet
Dim InsertedRows As System.Data.DataSet
Dim DeletedRows As System.Data.DataSet

UpdatedRows = ds.GetChanges(System.Data.DataRowState.Modified)
InsertedRows = ds.GetChanges(System.Data.DataRowState.Added)
DeletedRows = ds.GetChanges(System.Data.DataRowState.Deleted)

Try
da_vehicle.Update(UpdatedRows)
da_vehicle.Update(InsertedRows)
da_vehicle.Update(DeletedRows)
Catch updateException As System.Exception
MsgBox("Caught exception: " & updateException.Message)
End Try

Me.DbConnection.Close()
End Sub

Hecate

09-16-02, 04:44

When running the program I only test by updating a field... It means each field on the form is filled in.

Althought the error message is mentionning no Null value allowed. It's like it doesn't keep the link between the form and the dataset at the time of the update.

Weirder... If i change a field on the form... then move to another record, and only then perform the update, I receive the same error, but changes are applied to the database.

The Insert/update sequence doesn't work at all... even if I move back on another record before to perform the update. In all case I get the No Null Value allowed error and no change is applied to the DataBase.

Hecate.