DataSet

[Tony Johansson]

Hello!

This is also a working console program.
It seems to me that a DataSet is actually the result of the query as in my
example
because the result is from two tables.
Is this correct understood ?

What will happen if you change some row and then call the update for
DataAdapter object ?


static void Main(string[] args)
{
//Specify SQL Server-specific connection string
SqlConnection thisConnection = new SqlConnection(
@"Server=UHT-DEMO1; Integrated Security=True;" +
"Database=north wind");

//Create DataAdapter object
SqlDataAdapter thisAdapter = new SqlDataAdapter(
"Select Customers.Custo merID, OrderID, ContactName from
Customers, Orders " +
"where Customers.Custo merID = Orders.Customer ID and " +
"OrderID = 10248", thisConnection) ;

//Create DataSet to contain related data tables, rows and
columns
DataSet thisDataSet = new DataSet();

//Fill DataSet using query defined previously for DataAdapter
thisAdapter.Fil l(thisDataSet, "Test");

foreach (DataRow theRow in thisDataSet.Tab les["Test"].Rows)
Console.WriteLi ne("Row = {0}", theRow["CustomerID "] + "\t" +
theRow["ContactNam e"]);

thisConnection. Close();
Console.WriteLi ne("Program finished, press Enter/Return to
continue");
Console.Read();
}

[Ignacio Machin ( .NET/ C# MVP )]

Re: DataSet

On Aug 20, 6:43 am, "Tony Johansson" <johansson.ande rs...@telia.com >
wrote:

Hello!
>
This is also a working console program.
It seems to me that a DataSet is actually the result of the query as in my
example
because the result is from two tables.

It will have one table only. that is the result of the query

For updates you need to define the UpdateCommand of the dataadapter.

[Alberto Poblacion]

Re: DataSet

"Tony Johansson" <johansson.ande rsson@telia.com wrote in message
news:evq69$qAJH A.3756@TK2MSFTN GP04.phx.gbl...

This is also a working console program.
It seems to me that a DataSet is actually the result of the query as in my
example
because the result is from two tables.
Is this correct understood ?

You are returnig the result of joining two tables on the server. From
the point of view of the DataSet, you only have a single table (even though
the contents of that table came from two tables on the server, the DataSet
never sees this detail).

What will happen if you change some row and then call the update for
DataAdapter object ?

You will get an Exception, because your DataAdapter only contains a
SelectCommand, but not the UpdateCommand, InsertCommand, and DeleteCommand
that would be necessary if you needed to send changes to the database.

Even if you were to use a SqlCommandBuild er to try to build the missing
commands, it would still fail because those commands cannot be generated
automatically when the original query is a join. You would have to build
them yourself, and then "what would happen" would depend of what you wrote
into those commands.

[Tony Johansson]

Re: DataSet

Hello!

The object SqlCommandBuild er will automatically create an update command so
DataAdapter.upd ate will work for update.

//Tony

"Ignacio Machin ( .NET/ C# MVP )" <ignacio.machin @gmail.comskrev i
meddelandet
news:4be10dc2-1a61-450a-ad66-0c182f3744e9@y2 1g2000hsf.googl egroups.com...
On Aug 20, 6:43 am, "Tony Johansson" <johansson.ande rs...@telia.com >
wrote:

Hello!
>
This is also a working console program.
It seems to me that a DataSet is actually the result of the query as in my
example
because the result is from two tables.

It will have one table only. that is the result of the query

For updates you need to define the UpdateCommand of the dataadapter.