BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Deletion of a record in self referenced table          BorlandTalk.com Forum Index -> comp.lang.pascal.delphi.misc View previous topic :: View next topic   Author Message Prasad Kulkarni Guest Posted: Tue Nov 11, 2003 5:09 am    Post subject: Deletion of a record in self referenced table Hello All, I have a self referenced table with structure like Num Integer Text String Level Integer Parent Integer linked to Num Now if a parent record is deleted i have to delete all its children, children's children....etc. Is there any simple way to do this. Regards Prasad Back to top Jeremy Collins Guest Posted: Tue Nov 11, 2003 9:26 am    Post subject: Re: Deletion of a record in self referenced table Prasad Kulkarni wrote: Quote: Hello All, I have a self referenced table with structure like Num Integer Text String Level Integer Parent Integer linked to Num Now if a parent record is deleted i have to delete all its children, children's children....etc. Is there any simple way to do this. Your database engine might be able to do this using referential integrity, so if you set up your primary and foreign keys correctly this will happen automatically. If not, store the NUM in the dataset's BeforeDelete event, and in the AfterDelete event execute an SQL statement to remove the orphans: DELETE FROM tb_tree WHERE Parent = NUM_VALUE You will find future maintenance easier if you use more descriptive field names (ITEM_ID, ITEM_TEXT for example). And isn't "LEVEL" redundant? -- jc Remove the -not from email Back to top Bruce Roberts Guest Posted: Tue Nov 11, 2003 6:25 pm    Post subject: Re: Deletion of a record in self referenced table "Jeremy Collins" <jd.collins (AT) ntlworld-not (DOT) com> wrote Quote: If not, store the NUM in the dataset's BeforeDelete event, and in the AfterDelete event execute an SQL statement to remove the orphans: One might want to remove the children before removing the parent. This way if child removal fails for some reason one doesn't end up with invalid references. 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