archetecture query

archetecture query

1 hierachical Queries
 select [level],colun,expr......
 from table
 [where condition(s)]
 [start with condition(s)]
 [connect by prior condition(s)]
 
 where condition
  exprcompparison_operator expr

2 Starting Point
 .Specifies the condition that must be met
 .Accepts any valid condition
3 Waling the Tree
  connect by prior column1=column2
  walk from the top donw ,using the employees table
   top donw
     column1=parentkey
     column2=childkey
   bottom up
     column1=child key
     column2=parent key

  select level,last_name
  from employees
  start with last_name='king'
  connect by prior employee_id=manager_id;