How to add range in an executeQuery of a dataSource

Here is an example:

public void executeQuery()
{
    QueryBuildRange    queryBuildRange;
    ;
    queryBuildRange = Projcategory_ds.query().dataSourceTable(tablenum(Projcategory)).findRange(fieldnum(Projcategory,Categorytype));
    if(!queryBuildRange)
    {
        queryBuildRange = Projcategory_ds.query().dataSourceTable(tablenum(Projcategory)).addRange(fieldnum(Projcategory,Categorytype));

    }
    queryBuildRange.value(queryValue(ProjCategoryType::Item));
    super();
}