CURRENT_DATABASE()

Return the database for the current session.
CURRENT_DATABASE()
CURRENT_CATALOG

These functions are synonyms. CURRENT_DATABASE() requires the parentheses. CURRENT_CATALOG does not work with parentheses.

premdb=# select CURRENT_DATABASE();
 current_database 
------------------
 premdb
(1 row)
premdb=# SELECT CURRENT_CATALOG;
 current_database 
------------------
 premdb
(1 row)