Descending order in Form Task 5

To show the record in Descending order Task 5
IN the form-> DS-> init()
1 write the following code:
this.query().dataSourceNo(1).addSortField(fieldnum(DatasourceTable , field), SortOrder::Descending);
Example:
this.query().dataSourceNo(1).addSortField(fieldnum(CustTable,AccountNum) ,SortOrder::Descending);

2 In DS-> ExecuteQuery()
while select CustTable order by AccountNum desc
{
}