To delete the records which has 1-2-m relationship

chinni_77

Hello everybody,

I need some advice with one of my tasks.Here it goes....

I've got 3 tables(Topics, Subtopics, Articles) which are related to each other.

Each Topic has many Subtopics and each Subtopic has got many articles.

I want to design a form inorder to delete either a topic or a subtopic or an article.

Well, I've written a piece of code in order to delete the articles and its working fine.

What happens if I directly delete the subtopics though there are some articles exsisting under them??and similary with the topics if there are some sub-topics under their belt.

If this is gonna happen, I think the system will not be a stable one.My articles table look like(Article_id, Subtopic_id, Topic_id, Article_name Article_file, Article_keyword)

How best can I do inorder to make the system stable so that I can be able to delete a topic or a sub-topic or an article.

Thanks in advance

ccgorman

You just need to set up some logic.

If you are deleting a subtopic make sure you delete all articles with subtopic_id, and if you are deleting a topic make sure you delete all subtopics with topic_id and all articles with subtopic_id.

I would have three tables
Article
(Article_id, Article_name)

Subtopic
(Subtopic_id, Subtopic_name)

Article
(Article_id, Subtopic_id, Article_name, Article_file, Article_keyword)

If you want to upgrade your system to have as many subtopics within subtopics as you wish then modify it as so:

Article
(Article_id, Parent_id, Topic_name)

(this will allow threads, i.e. a topic, with a subtopic with a subsubtopic... and it gets rid of the need for three tables, just the two)

Arc

To delete a Topic you would need to get the topic ID to be deleted then goto the Articles Table and delete every article that has that topic ID, then goto the subtopic table and delete every subtopic that has that Topic ID then finaly delete that topic.

chinni_77

OK, here how I would like to do now.

First, I'l display all the topic names and next to each topic name there'll be a check box.Once, when the user checks this check box and hit the button delete, the record is deleted.But, before the records get deleted, is it possible to make a look up on the sub-topics table so that if there are sub-topics related to this topic_id then the record should not be deleted instead it has to show some error mesg.
Is that possible, if so, could somebody please give me a start up.

Many thanks