Re: row numbering
От | Marcin Inkielman |
---|---|
Тема | Re: row numbering |
Дата | |
Msg-id | Pine.LNX.4.21.0005102350330.23669-100000@mi.marnnet обсуждение исходный текст |
Ответ на | Re: row numbering (Peter Eisentraut <peter_e@gmx.net>) |
Список | pgsql-general |
Hi! thanks for your respose! sorry if i was not very clear with my question... On Wed, 10 May 2000, Peter Eisentraut wrote: > Marcin Inkielman writes: > > > how may i easyly obtain row numbers in a query: > > In the SQL data model, rows don't have numbers, because rows aren't > ordered -- a query may return the rows in any order. So if you are sure, i know that > building on that assumption you might have to rethink slightly. > > If you need to number your records for some reason, say invoice numbers, > you can use a sequence: that is exactly i want to obtain. i would like to have: 1 | first item 2 | second, 3 | ... and so on. each time i do a select on a table and aways starting with a "1". > > create table my_tbl ( > nr serial, -- creates implicit sequence > ... more fields ... > ); > > Then you can select them like any other field. You say you had > unsatisfying results, would you care to explain why? the main problem i have with sequences (or temporary tables - as i think you suggest) is that i have multiples concurrent transactions at he same time. as they are generated by a single cgi script, if i use a sequence it will have the same name for each transaction, and therefore only the first trasaction will work. of course i may lock it just like a simple table but i am not sure this is a simpliest way. i am just searching something simplier > > Lastly, there is the OID which every row gets automatically assigned by > the system. This is a unique number across the whole installation. You can > access it as > select oid, your, fields, here from table ... > like a regular column. The OID may be good enough to get some sort of > number on a row but be aware that it is wildly non-portable. i thought to use oids but i am no sure if it is possible to obtain the result i require > > > Marcin Inkielman
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