Re: how to create an index on serial column

Sally Woolrich <Sally@excelsis.demon.co.uk> wrote: >In article <41l8co$rtu@eccdb1.pms.ford.com> > mreed@ese721 "Michael Reed - Radiix" writes: > >> Steve Morrow (smorrow@dotrisc.cfr.usf.edu) wrote: >> : A unique index is automatically built on a serial column. >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >> This is not true. >> A serial column doesn't guarantee uniqueness. An index is not auto- >> matically built. >> >> The only way to guarantee uniqueness is to build a unique index >> on that column. I can't answer why alter table is giving him trouble, though. > >I think that it *is* true that each value in a serial column is unique, >but it is *not* true that there is an index unless you explicitly >build one - certainly if using 'CREATE TABLE' statements to create >a table (there is another way of creating them hidden *somewhere* >in the 'dbaccess/'isql' ring menu structures). > >-- >============================================================================ >Sally Woolrich | This mail contains my personal >sally@excelsis.demon.co.uk | views not those of my employer! >============================================================================ The Table created with dbaccess has a unique constraint automatically added. 'create table ...' does not. The SERIAL will still be unique as long as 2^31 rows are not exceeded, then there is a wrap-around (This assuming you don't mess around with 'alter table' to reset the 'next' value, or set it in the 'create ..'). This quotes the Manual T 9-9 Version 7.1. I hope this is true Andreas Zeugswetter