Oracle Database Discussions

1. What's the differences between CAT and TAB?
2. Why doesn't TAB exist in dict?
3. What the appropriate situation for CAT and TAB?

Thanks a lot for your kindly reply.

sys@ORCL> desc cat
Name Null? Type
----------------------------------------------------- -------- ------------------------------------
TABLE_NAME NOT NULL VARCHAR2(30)
TABLE_TYPE VARCHAR2(11)

sys@ORCL> desc tab
Name Null? Type
----------------------------------------------------- -------- ------------------------------------
TNAME NOT NULL VARCHAR2(30)
TABTYPE VARCHAR2(7)
CLUSTERID NUMBER

sys@ORCL> select * from dict where table_name='CAT';

TABLE_NAME COMMENTS
---------- -----------------------------------
CAT Synonym for USER_CATALOG


sys@ORCL> select * from dict where table_name='USER_CATALOG';

TABLE_NAME COMMENTS
-------------------- -----------------------------------------------------------------
USER_CATALOG Tables, Views, Synonyms and Sequences owned by the user