The following 2 queries are different only w/ or w/o "as 'test'".

Oracle server and client info:
SQL*Plus: Release 9.2.0.1.0 - Production on Fri May 20 10:44:37 2005

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.


Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning, Oracle Label Security, OLAP and Oracle Data
Mining options
JServer Release 9.2.0.4.0 - Production

SQL> select case when sysdate is null then 'nulldate'
2 else to_char(sysdate) end as 'test'
3 from dual;
else sysdate end as 'test'
*
ERROR at line 2:
ORA-00923: FROM keyword not found where expected



1 select case when sysdate is null then 'nulldate'
2 else to_char(sysdate) end
3* from dual
SQL> /

CASEWHENS
---------
20-MAY-05

You need to either use double quotes or no quotes at all around test,
not single quotes. Please see the examples below.

scott@ORA92> select case when sysdate is null then 'nulldate'
2 else to_char (sysdate) end as test
3 from dual
4 /

TEST
---------
20-MAY-05

scott@ORA92> select case when sysdate is null then 'nulldate'
2 else to_char (sysdate) end as "test"
3 from dual
4 /

test
---------
20-MAY-05

scott@ORA92>