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NOW() - Start Time of Execution
How to obtain the start time of an execution unit using the NOW() function?
✍: FYIcenter.com
NOW(prec) is a MySQL built-in function that returns the start time of an execution unit with a given precision of fractional seconds. For example:
SELECT NOW(), SLEEP(2), NOW(); -- +---------------------+----------+---------------------+ -- | NOW() | SLEEP(2) | NOW() | -- +---------------------+----------+---------------------+ -- | 2023-11-22 11:43:07 | 0 | 2023-11-22 11:43:07 | -- +---------------------+----------+---------------------+ SELECT NOW(), NOW()+1; -- +---------------------+----------------+ -- | NOW() | NOW()+1 | -- +---------------------+----------------+ -- | 2023-11-22 12:02:40 | 20231122120241 | -- +---------------------+----------------+ SELECT NOW(6), NOW(6)+1; -- +----------------------------+-----------------------+ -- | NOW(6) | NOW(6)+1 | -- +----------------------------+-----------------------+ -- | 2023-11-22 12:03:08.505415 | 20231122120309.505415 | -- +----------------------------+-----------------------+
Note that NOW() returns the start time of an execution unit like a statement, a stored function or a trigger. Calling NOW() multiple times will give you the same timestamp.
SELECT NOW(), SLEEP(2), NOW(); -- +---------------------+----------+---------------------+ -- | NOW() | SLEEP(2) | NOW() | -- +---------------------+----------+---------------------+ -- | 2023-11-22 12:05:07 | 0 | 2023-11-22 12:05:07 | -- +---------------------+----------+---------------------+
Reference information of the NOW() function:
NOW(prec): tm Returns a constant time that indicates the time at which the statement, a stored function or a trigger, began to execute. Returns the current timestamp as a value in 'YYYY-MM-DD hh:mm:ss.SSSSSS' or YYYYMMDDhhmmss.SSSSSS format, depending on whether the function is used in string or numeric context. Arguments, return value and availability: prec: Optional. Default is 0. The precision of fractional seconds. tm: Return value. The start time of the execution unit. Available since MySQL 4.
Related MySQL functions:
⇒ PERIOD_ADD() - Adding Months to Period
2023-11-17, 255🔥, 0💬
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