On 01/24/2013 01:06 PM, Chris Angelico wrote:
> On Fri, Jan 25, 2013 at 4:45 AM, Steve Clark <sclark@netwolves.com> wrote:
>> Thanks All,
>>
>> This is for a few very small tables, less 100 records each, that a user can
>> delete and insert records into based on the "id"
>> which is displayed in a php generated html screen. The tables are rarely
>> updated and when they are updated only one person
>> is accessing them at a time.
>>
>> I have seen several answers on inserting what about deleting?
> Deleting works exactly the same way; you just subtract instead of adding.
>
> And thanks Jeff, I forgot about that requirement. Still, searched
> update is the easiest solution.
>
> However, do seriously rethink your design. At very least, the "id"
> field is misnamed; it's not the record's identity if it changes. If
> your only two operations are "insert" and "delete" (with inserts
> permitted at either end of the list as well as in the middle), one way
> you could do it is to have a serially-numbered ID, and a 'pos'. Adding
> to the end means inserting a row with a pos one higher than the
> current highest. Inserting a record before another one means inserting
> a row with the same pos - no renumbering needed. Deleting a row is
> done by its id, not its position. And when you query the table, just
> ask for them "ORDER BY POS, ID DESC" - this will show them in the
> right order. This doesn't, however, handle arbitrary reordering of
> records. For that, you will ultimately need to renumber the positions.
>
> ChrisA
>
>
Hi Chris,
It is really called rule_num and relates to "in what order firewall rules are applied". And it used
to allow the user to place the firewall rules where they want them in relation to other rules.
This is an old design, of which I had no input, but am now maintaining. Like I said initially I have
php, bash or C code to do the reordering and was just wondering if there was a slick way to
do it without having to resort to some external mechanism.
Thanks to all who responded.
--
Stephen Clark
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