How to sort data in DataSet

You shouldn't use the DefaultView property instead you should create a new DataView. The reason for creating a new is;
it doesn't work when setting the property to "DefaultView" is because you have to access the DefaultView, not the DataSet to get the sorted results. Manipulating the DefaultView is usually not a good idea.

Basically, create a new instance of the DataView class and pass that around after you set the sort, and work with that.

//open the connection
sqlConnection.Open();

//create a new sqladapter and set its command object with our sqlcommand
SqlDataAdapter sqlAdapter = new SqlDataAdapter(sqlCommand);
//create a new dataset to hold our data
DataSet ds = new DataSet();
//fill the dataset with the result of our query from the specified command
sqlAdapter.Fill(ds);

//create a new dataview from our table in our dataset at index 0
DataView dv = new DataView(ds.Tables[0]);

//apply our row filter. get only records with a lastname of 'Callahan'
dv.RowFilter = "Name = 'Brown'";

//close our connection
sqlConnection.Close();

//return our dataview
return dv;

for a reference see this link;

Sort datatable[^]