Re: INFORMIX & DATA TYPE SERIAL: Questions
In article <6aj2md$5b7@cssun.mathcs.emory.edu>, sujata_soman_at_omm- la2-infotech-001@internet.omm.com writes > >Hi all, > Some questions on how Informix handles the "Serial(n)" data type. > >1. How is the "next serial number" calculated ? why do I sometimes see different >behaviour(s), for eg, if we have 5 rows, numbered 1 thru 5, and I delete #5, and >insert a new row :- On some occasions, the new serial number is #5, and on >others, it is #6 - Why ? > I is NOT documented what the next number will be only that it will be unique. Normally I expect it to go up by one each time. >2. I once deleted all the rows in a table with a serial number field, and when I >tried to insert new rows, the serial number had not been updated to 0, ie the >new numbers picked up from the old set. > Correct, Informix just adds one to the last number used. >3. Now, when you create a new table with a serial type column, if you do not >specify an initial number ( for eg serial(2) vs serial ), does that default to >0 ?? Default starting value is 1. Inserting 0 means use the next number. > >4. Are the "holes" in a serial type column ever filled/re-used ?? > If serial gets too large (2 to the power 32) it will wrap again to 1. If 1 is used the you get an error. (This was confirmed by someone a while back - John L(?)). If after it wraps 1 works I would expect the same behaviour for 2 i.e. it is used if it is not already in use otherwise you get an error..smae for 3,4,5 etc.. >TIA > >Sujata > >***************************************** > Sujata Soman > > > E-Mail: ssoman@omm.com > > O'Melveny & Myers, Los Angeles > >****************************************** > > > > > > > > > -- David Williams Maintainer of the Informix FAQ Primary site (Beta Version) http://www.smooth1.demon.co.uk Official site http://www.iiug.org/techinfo/faq/faq_top.html I see you standin', Standin' on your own, It's such a lonely place for you, For you to be If you need a shoulder, Or if you need a friend, I'll be here standing, Until the bitter end... So don't chastise me Or think I, I mean you harm... All I ever wanted Was for you To know that I care