OK, so Sybase (12.5.4) will let me do the following to DROP a table if it already exists:
IF EXISTS ( SELECT 1 FROM sysobjects WHERE name = \'a_t
This works when tested with Sybase anywhere 10.01 :
if not exists(select * from SysColumns where tname = 'AAA') then create table DBA.AAA( UNIQUEID integer not null ) END IF ;