sql树问题

Question

Parent                             Child                             
---------------------------------- ----------------------------------
World                              Europe                            
World                              North America                     
Europe                             France                            
France                             Paris                             
North America                      United States                     
North America                      Canada                            
United States                      New York                          
United States                      Washington                        
New York                           New York City                     
Washington                         Redmond                           
如何实现下边的查询结果
World
   North America
      Canada
      United States
         Washington
            Redmond
         New York
            New York City
   Europe
      France
         Paris

Answer 1

--have a try! select parent,Lpad(' ',6*(Level-1))||child as child
 from 表
 start with parent='World'
 connect by parent=prior child;