What is the difference between datetime and timestamp in mysql?

In MySQL, both datetime and timestamp are data types used to store date and time information, but they have some important differences.

1. The range for datetime data type is from ‘1000-01-01 00:00:00’ to ‘9999-12-31 23:59:59’, while the range for timestamp data type is from ‘1970-01-01 00:00:01’ UTC to ‘2038-01-19 03:14:07’ UTC. Therefore, the timestamp type is limited in its storage range.
2. Storage space: The datetime data type requires 8 bytes of storage space, while the timestamp data type only requires 4 bytes. This means that when storing the same amount of data, the timestamp data type will take up less space.
3. Storage method: The value stored in datetime type is independent of time zone, while the value stored in timestamp type is time zone-dependent. This means that the value stored in datetime type will not change with the change of time zone, while the value stored in timestamp type will be adjusted according to different time zones.
4. Automatic update: In MySQL, you can add the DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP attributes to a timestamp column to enable automatic updating. When inserting a new row or updating an existing row, the timestamp column will automatically update to the current date and time. This feature is not available for datetime columns.

One should choose between using datetime and timestamp types based on specific needs. If needing to store timezone-independent dates and times with a larger range, datetime type may be preferred. If needing to store timezone-related dates and times with a smaller range, timestamp type may be more suitable.