Обсуждение: How to select by proximity

On 2012-05-14 14:00, Francisco Leovey wrote:
> Hello group
>
> I have a large table indexed by a varchar column
> I would like to select records that are around the hit value, say
> "Marriot" by index order
> How can I retrieve the prior and next in order?
> Is there a goto "Marriot" and then a goto +1 and goto -1 SQL
> facility?

The LIMIT and OFFSET commands in a SELECT statement (in combination
with ORDER BY) should be helpful here.

However, it's important to remember the the database has no real
concept of 'index order': All data is unordered unless ask it to be
ordered.  It's not going through a list until it gets to 'Marriot', and
then returning that to you; it's returning a set which includes
'Marriot'.  To do what you want, you'll likely need to return the
*entire* table, and then pull out what parts you want.  The LIMIT and
OFFSET would only be helpful once you know where 'Marriot' appears in
the (ordered) result of your particular query at a particular point in
time.

Daniel T. Staal

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Can OFFSET be a negative number?

What I was looking for is a way to access the +1 and -1 record with SQL as seen on the screen when you do a select using an index or a sort.

With PgAdmin when you  see a record of interest in the middle of the display, you can visually see the one above and below.

I seem to remember that in Informix I had a go + or -  inside a pointer loop.