David Newall wrote:
> PostgreSQL version: 7.4.3 (RPMs from ftp.au.postgresql.org)
>
> Operating Sysem: Fedora Core 1
>
> CREATE TABLE t(i integer UNIQUE);
> INSERT INTO t VALUES (null);
> INSERT INTO t VALUES (null);
> SELECT coalesce(i,-999) FROM t;
> coalesce
> ----------
> -999
> -999
> (2 rows)
NULL = NULL is not true, so the rows are not equal.