TIMESTAMPDIFF
TIMESTAMPDIFF is a function used in SQL databases to calculate the difference between two date or time values. It is particularly useful for measuring intervals in days, hours, minutes, seconds, or other time units. The function takes three arguments: the unit of time to be measured, the start date or time, and the end date or time. The unit of time can be specified using keywords such as 'YEAR', 'MONTH', 'DAY', 'HOUR', 'MINUTE', 'SECOND', 'MICROSECOND', 'QUARTER', 'WEEK', 'SECOND_MICROSECOND', 'MINUTE_MICROSECOND', 'MINUTE_SECOND', 'HOUR_MICROSECOND', 'HOUR_SECOND', 'HOUR_MINUTE', 'DAY_MICROSECOND', 'DAY_SECOND', 'DAY_MINUTE', 'DAY_HOUR', 'YEAR_MONTH', and 'QUARTER'. For example, TIMESTAMPDIFF(DAY, '2023-01-01', '2023-01-10') would return 9, indicating the difference in days between the two dates. This function is widely supported in various SQL databases, including MySQL, PostgreSQL, and SQL Server, although the syntax and supported units may vary slightly between systems. It is a valuable tool for performing date and time calculations in SQL queries.