Unix time is defined as the number of seconds that have elapsed since midnight Coordinated Universal Time (UTC), 1 January 1970,not counting leap seconds. It is used widely in Unix-like and many other operating systems and file formats. It is neither a linear representation of time nor a true representation of UTC. Unix time may be checked on some Unix systems by typing date +%s on the command line.Sometimes it's a bit difficult to compare times stored in different applications or systems with different formats. For example, if we want to compare a DATE in Oracle with a date string in Unix, we...