RE: Enforced Costraints ??

Anshuman,

whenever u add a constraint to a table, oracle will make sure all the data (if any)
confirms to the constraint added....

you can enable or disable a constraint (even defer)... dont confuse urself with the term "enforcing a constraint".

Regards
Rahul

> ----------
> From: Anshumn[SMTP:anshumn.sagar_at_wipro.com]
> Sent: Tuesday, June 12, 2001 11:26 AM
> To: LazyDBA.com Discussion
> Subject: Enforced Costraints ??
>
> Hi gurus,
>
> Please help me to know the difference between enabling and enforcing a
> constraint. I need it urgently.
>
> As per my knowledge, enabling a constraint checks for the
> existing data to apply that constraint and then the constraint is
> applied for the forthcoming data. Whereas enforcing a constraint does
> not check the existing records and the constraint is only applied to the
>
> forthcoming data only. Is it correct ?
>
> Suppose I have a 'unique' constraint. If I enforce this constraint, then
>
> for checking the uniqueness criteria, will not it check the existing
> records to determine whether the coming record is unique or not ? If it
> checks for the uniqueness among the forthcoming records only, then I
> have a doubt. In this case I may have loaded a record, with a value
> which is already present in the existing data(Since the existing data
> was not checked while enforcing the constraint). Now if I enable the
> constraint, then that time it will check all the records for uniqueness.
>
> How does it work in that case ? Won't it give me an error ? Then how
> good is the use of an enforced constraint ?
>
> Please give your valuable feedback to clear this doubt. I need it
> urgently.
>
> Thanks in advance,
> Anshumn
>
>
>
> --------
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