Check database uptime

Sometimes you have to check when a database was started for the last time. To get the information, just log on to the database and use the following query to get the last startup time:

On Oracle database

SELECT to_char(startup_time,'DD-MON-YYYY HH24:MI:SS') AS "DB Startup Time"
FROM   sys.v_$instance;

On Mysql database

SHOW GLOBAL STATUS LIKE 'Uptime';

This simple trick can be useful to troubleshoot when a database was unavaliable at some point and is now accessible. Using this simple command you’ll be able to tell if the database has been restarted.