When selecting DATETIME and TIMESTAMP types in MySQL, they should be determined based on time zone processing, automatic update, time range, storage space and concurrency requirements. 1. If you need to automatically convert the time zone, you should select TIMESTAMP, which will automatically adjust the display time according to the connection time zone, and DATETIME will always remain the same; 2. If you need to update the fields automatically, TIMESTAMP supports ON UPDATE automatic refresh, and DATETIME only supports the default value; 3. If you need a larger time range (1000 to 9999), select DATETIME, which has a smaller range (1970 to 2038); 4. If you are sensitive to storage space, TIMESTAMP takes up 4 bytes and saves space; 5. DATETIME is recommended for high concurrent writes or distributed systems to avoid time zone and performance problems. Reasonable choices are key in combination with business scenarios.

When selecting DATETIME and TIMESTAMP types in MySQL, many people will confuse their applicable scenarios. In fact, the key difference lies in the purpose and behavior: DATETIME is "literal time", while TIMESTAMP is "timestamp", which is affected by the time zone. Which one you choose depends on what time you save, whether it needs to be updated automatically, and whether it is used across time zones.

1. Check whether the time zone needs to be automatically converted

This is one of the most core differences between the two:

• TIMESTAMP will automatically convert stored values ??according to the time zone of the current connection.
• DATETIME No matter where you are, you will be like depositing it in, and you will find it out.

For example:
If you write a record in East Eighth District 2025-04-05 12:00:00 , and then use the client of East Eighth District to check:

• If the field is TIMESTAMP , it may be found to be 2025-04-05 09:00:00 (because it is 3 hours apart)
• If it is DATETIME , it is still found out that it is still 2025-04-05 12:00:00

So, if your data is to be displayed to users in different regions and hope they see the local time, then using TIMESTAMP is more appropriate; if time is only used to record a certain fixed moment (such as log time), then using DATETIME .

2. Check whether the automatic update function is required

MySQL supports automatic update of TIMESTAMP fields, such as:

 CREATE TABLE example (
    id INT PRIMARY KEY,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

The above structure is very suitable for recording the creation time and the last modification time.

Although DATETIME also supports DEFAULT NOW() as of MySQL 5.6, it does not support automatic updates (ON UPDATE). If you want to implement automatic update logic with ease, then TIMESTAMP is more convenient.

3. Look at the time range and storage space

• DATETIME can represent a larger time range: from 1000-01-01 00:00:00 to 9999-12-31 23:59:59
• TIMESTAMP has a smaller range: from 1970-01-01 00:00:01 UTC to 2038-01-19 03:14:07 UTC

in addition:

• DATETIME accounts for 8 bytes
• TIMESTAMP accounts for 4 bytes

If you don't need that far (such as order creation time, user registration time, etc.), using TIMESTAMP can save a little space and is more compact.

4. Are there a large number of concurrent writes or high-precision requirements?

Here is a small detail that is easily overlooked:
Starting with MySQL 5.6.5, both types support millisecond precision (in microseconds (6) ), but TIMESTAMP(6) may encounter performance bottlenecks when handling large numbers of concurrent insertions, especially when multiple nodes write to simultaneously in distributed systems.

At this time, DATETIME(6) is recommended because it will not depend on the server's time zone configuration, nor will it cause repeated write problems due to time zone changes.

Basically these considerations.
Let's briefly summarize:

• Want to automatically handle time zones? Choose TIMESTAMP
• Need automatic update? Priority TIMESTAMP
• Does it matter if the time range is large and it doesn’t matter if it crosses time zones? Use DATETIME
• Sensitive to storage space? TIMESTAMP is more efficient
• High concurrent writes or require stability? Probably better for DATETIME

When choosing, combine your business scenarios and don’t just look at the default habits.

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