Attach a DataTable to a DataSet

I have a business object that return the list of contacts to the user
interface. Here is the code of the method:

public DataTable getContact ()
{
// I know, this part should be in the Data Layer...

SqlConnection conn = new SqlConnection (...);
DataSet dsContact = new DataSet ();
SqlDataAdapter adptContact = new SqlDataAdapter ("SELECT * FROM
Contact ORDER BY Contact", conn);
adptContact.Fill (dsContact, "Contact");
return dsContact.Tables ["Contact"];
}

The user interface should get the list and add it to it's DataSet. A
control will then be bounded to this list.

I have some questions:

- Must I pass through a DataSet and a DataAdapter class to fill a DataTable?
- I return a DataTable instead of a DataSet because I figure that it is
smaller and should be faster. Am I right in this assumption?
- When a DataTable (or DataSet) is passed like this between layers, what
is really passed between the EXE and the DLL, a XML string or the object
is marshalled and passed?
- In the user interface, I would like to put all the tables I get like
this in a DataSet instead of defining a property for each one, but I
can't get the DataSet to add the DataTable. Here is the code:

Contact contact = new Contact ();
DataTable dtContact = contact.getContact ();
dsMain.Tables.Add (dtContact); // Exception is throwed here

Any suggestions?

TIA

Elton
Fri Mar 11 21:14:00 CST 2005

You can try directly fill data table in method getContact:

public DataTable getContact ()
DataTable contactTable = new DataTable();
SqlDataAdapter adptContact = new SqlDataAdapter("SELECT
* FROM Contact ORDER BY Contact", CONNECTION_STRING);
adptContact.Fill(contactTable);
return contactTable;
}

HTH

Elton Wang
elton_wang@hotmail.com


>-----Original Message-----
>I have a business object that return the list of contacts
to the user
>interface. Here is the code of the method:
>
>public DataTable getContact ()
>{
> // I know, this part should be in the Data Layer...
>
> SqlConnection conn = new SqlConnection (...);
> DataSet dsContact = new DataSet ();
> SqlDataAdapter adptContact = new SqlDataAdapter
("SELECT * FROM
>Contact ORDER BY Contact", conn);
> adptContact.Fill (dsContact, "Contact");
> return dsContact.Tables ["Contact"];
>}
>
>The user interface should get the list and add it to it's
DataSet. A
>control will then be bounded to this list.
>
>I have some questions:
>
>- Must I pass through a DataSet and a DataAdapter class
to fill a DataTable?
>- I return a DataTable instead of a DataSet because I
figure that it is
>smaller and should be faster. Am I right in this
assumption?
>- When a DataTable (or DataSet) is passed like this
between layers, what
>is really passed between the EXE and the DLL, a XML
string or the object
>is marshalled and passed?
>- In the user interface, I would like to put all the
tables I get like
>this in a DataSet instead of defining a property for each
one, but I
>can't get the DataSet to add the DataTable. Here is the
code:
>
>Contact contact = new Contact ();
>DataTable dtContact = contact.getContact ();
>dsMain.Tables.Add (dtContact); // Exception is throwed
here
>
>Any suggestions?
>
>TIA
>.
>

Robbe
Sat Mar 12 11:48:11 CST 2005

Your getContact method is already establishing a reference
to a DataSet. Make that method fill a datatable instead of a
dataset and you should be fine. I do this sort of thing
all the time in my apps.

--
2005 Microsoft MVP C#
Robbe Morris
http://www.robbemorris.com
http://www.masterado.net/home/listings.aspx



"Sylvain Larin" <slarin@NOSPAM_gmail.com> wrote in message
news:%23y5uzEoJFHA.2356@TK2MSFTNGP14.phx.gbl...
>I have a business object that return the list of contacts to the user
>interface. Here is the code of the method:
>
> public DataTable getContact ()
> {
> // I know, this part should be in the Data Layer...
>
> SqlConnection conn = new SqlConnection (...);
> DataSet dsContact = new DataSet ();
> SqlDataAdapter adptContact = new SqlDataAdapter ("SELECT * FROM Contact
> ORDER BY Contact", conn);
> adptContact.Fill (dsContact, "Contact");
> return dsContact.Tables ["Contact"];
> }
>
> The user interface should get the list and add it to it's DataSet. A
> control will then be bounded to this list.
>
> I have some questions:
>
> - Must I pass through a DataSet and a DataAdapter class to fill a
> DataTable?
> - I return a DataTable instead of a DataSet because I figure that it is
> smaller and should be faster. Am I right in this assumption?
> - When a DataTable (or DataSet) is passed like this between layers, what
> is really passed between the EXE and the DLL, a XML string or the object
> is marshalled and passed?
> - In the user interface, I would like to put all the tables I get like
> this in a DataSet instead of defining a property for each one, but I can't
> get the DataSet to add the DataTable. Here is the code:
>
> Contact contact = new Contact ();
> DataTable dtContact = contact.getContact ();
> dsMain.Tables.Add (dtContact); // Exception is throwed here
>
> Any suggestions?
>
> TIA