Is there a way using Hibernate to query the database for the database server's current time? This is particularly useful when needing to synchronize data on multiple client machines each running a Hibernate application with a centralized time residing on the database server.

Hibernate version: 3.0

Mapping documents: N/A

Code between sessionFactory.openSession() and session.close(): N/A

Full stack trace of any exception that occurs: N/A

Name and version of the database you are using: N/A

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In general, using time/date to synchronize is troublesome and error prone. With that disclaimer :

If you only want to work with a single server db (or a couple) then you might try :

DatabaseMetaData meta = connection.getMetaData();
// Get the list of time and date functions
String timedateFunctions[] = meta.getTimeDateFunctions().split(",\\s*");

This will give you a list of the db specific functions provided by the database and you might find one that's useful. You could also write a stored proc for the database that updates last-sync-time for a client at the end of your data generation. Then use that to select new data on next sync.

Another option would to create a view in the database that returns the current time. You could then query the view using Hibernate as if it were a table. For example, in Oracle the view could be one of:

CREATE VIEW CURRENT_TIME AS SELECT SYSDATE CURRENT_TIME FROM DUAL;

CREATE VIEW CURRENT_TIMESTAMP AS SELECT SYSTIMESTAMP CURRENT_TIMESTAMP FROM DUAL;

HQL has the following functions:

current_date(), current_time(), current_timestamp()

See http://www.hibernate.org/hib_docs/v3/reference/en/html_single/#queryhql-expressions

Assuming that I have acquired the db specific function name, how do I go about executing it from within Hibernate?