Question

I have a table called Module.
The table structure some things like:

ModuleID     ModuleName        ParentID

   1            System Manage       0
   2            Database Manage     1
   3            Area Manage         1
   4            Basic Setting       0

I would like to get the results below by a sql statement.

   ModuleID       ModuleName        ParentMoudle
     1               System Manage      0
     2               Database Manage    System Manage
     3               Area Manage        System Manage 
     4               Basic Setting      0

I am a sql newbie .Thank you very much!

Answer 1

Parent child relationship can be achived by LEFT OUTER JOIN and querying same table.

      select m.moduleid,m.modulename,COALESCE(p.modulename,0) from table as m
      left outer join table as p on m.moduleid = p.module.id