[V4RB] ? about cascade deletion and many to many relationship

[Ruslan Zasukhin]

on 2/7/03 12:07 AM, Kevin Windham at kevo at gatorgraphics.com wrote:

> No, You are right. And from what Ruslan said, I don't have to worry
> about it deleting records from t2.
> 
> However, Maybe Ruslan could explain what is meant by this in the
> ValentinaKernel.pdf doc (VKernel-30).
> 
> CASCADE ­ the One record is deleted and all related with it Many records are
> deleted also. If a Many record also have related Many records in the third
> Table(s) then they are also deleted. In other words we have cascade deletion.
> 
> To me that means that records in t2 would be deleted. That's where I
> got my confusion from to start with.

I see where from confusion come.

Look,

In your case you have tables:

        M  ->  1   <-  M

But above paragrah say about case:

        1 <- M <- M

For example:

        school -- group  -- student

If you delete now school then will be deleted all its groups and each group
will delete all its student.

CASCADE works in ONLY direction  1 - M.


-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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