Manipulating data between data adapters

Similar Threads:

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

Here's what I'm trying to do:

1. Create a data adapter with Select and Insert commands.

2. Use DataTableMappings to map XML tags into columns in a 
data base table.

3. Create a dataset

3. Read in a schema using dataset.ReadXmLSchema

4. Read in an xml file that contains the data using 
dataset.Read XML

5. Add 3 new columns to the dataset. (These columns have 
already been mapped in step 2).

6. Put data in the 3 new columns.

7. Modify some data in the other columns using xpath 
queries to find the nodes that need changing.

8. Use datadapter.update(dataset, tablename)

Everything seems to work fine until step 8. I get all the 
data, the extra columns get added, and the data in other 
columns gets modified. When I execute step 8 I get:

Run-time exception thrown : 
System.InvalidOperationException - Cannot add or remove 
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 
way.

TIA,
Candi

2.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
        Try
            If OleDbConnection1.State = ConnectionState.Closed Then
                OleDbConnection1.Open()
            Else
                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
            MsgBox(ex.Message)
        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
        DataSet11.Tables("Table1").Rows.Add(dr)
        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) "

3.Manipulate Data in a data set

Sorry if this is a basic question but I was wondering how to test the
dataset information as it is being read.

ex, I have a table that contains file extentions such as .xls, .doc,
.ppt. What I want to do is test the dataset as they are being written
and if the dataset is equal to .xls i want it to be excel..


I am new to this and am able to connect to the table but I just can
seem to get a handle on how to test the current dataset record and make
any changes. any bump in the right direction would be helpful ...
thanks in advance

4.Provider independent data access: creating a data adapter from a connection

I have written a provider independent ado.net utility class for 
executing queries. One of the routines looked like this in .net 1.1:

static public DataSet ExecuteQuery(IDbConnection connection, String sql)
{
   connection.Open();

   DataSet result  = new DataSet();
   IDbDataAdapter adapter = /* magic to create an adapter from a 
connection*/

   // The sybase adapter's implement IDisposable, so wrap with a using. 

   using(adapter as IDisposable)
   {
     adapter.SelectCommand.CommandText = sql;
     adapter.SelectCommand.Connection = conn;
     adapter.Fill(result);
   }

   return result;
}

The magic code to create the adapter was ugly: it essentially performed 
a dictionary lookup on the type of connection, and created the resulting 
adapter type. If IDbConnection had a method called CreateAdapter, 
analagous to CreateCommand, this would have been cleaner.

With the introduction of ADO.NET 2.0 and the DbProviderFactory class, I 
was hoping that some of the ugliness would go away. Unfortunately, I am 
running into some problems. Namely

1- DbConnection still does not have a CreateAdapter method

2- DbConnection does not offer a way to get back to the 
DbProviderFactory that created it.

So I still cannot create the correct adapter given only a generic 
DbConnection. I am looking for suggestions on how to code my routine. So 
far, I have thought of these

1- Make the user pass in the DbProviderFactory that goes with the 
connection. CONS: forces users to use DBProviderFactory. We have a lot 
of code that doesn't.

2- Stick with the dictionary lookup (Dictionary<ConnType, AdapterType>. 
CONS: DLL dependencies explode.

3- Use a different dictionary lookup (Dictionary<ConnType, 
DBProviderFactory>. CONS : A little messy, but better than 2.

4- Don't use provider specific adapters at all, just use a generic one. 
Like this:

class GenericAdapter : System.Data.Common.DbDataAdapter
{
}

static public DataSet ExecuteQuery(DbConnection connection, String sql)
{
   connection.Open();

   DataSet result  = new DataSet();
   GenericAdapter adapter = new GenericAdapter();
   adapter.SelectCommand = conn.CreateCommand();
   adapter.SelectCommand.CommandText = sql;
   adapter.Fill(result);
   return result;
}

I have tested this with two databases, Sybase ASE and ASA, and it seems 
to work. Are there any serious downfalls to not using the vendor 
specific adapter type? Is this code safe?

H^2

5.Passing parameter for Stored Procedure to Data Adapter/Data Se

6. Passing parameter for Stored Procedure to Data Adapter/Data Set

7. How to change data in grid after you change the SQL select for the data adapter

8. 3rd Tier data not displaying in Data Adapter Preview