Why can I use the int type for the time field in the mysql database? what are the advantages of the datetime type? What should I do?

Why can I use the int type for the time field in the mysql database? what are the advantages of the datetime type? I have seen some mysql database designs, such as the time field in the phpwind Forum, using int (10 )? It indicates that the time already has the datetime type. why should we use the int type? What are the advantages of doing so? I hope you can give me some advice. Why can I use the int type for the mysql database to indicate the time field? what are the advantages compared with datetime?
I have seen some mysql database designs, such as the time field in the phpwind Forum, using int (10 )? It indicates that the time already has the datetime type. why should we use the int type? What are the advantages of doing so? I hope you can give me some advice ~

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If there is a time zone problem, int type is used ..
If it is easy to read, use the datetime type...
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Because? Phpwind sorting is based on lastpost
Int type is much faster than varchar when the data volume is large

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Possible advantages:
1. sorting well. for example, if I want the latest news records, I just need to sort desc.
2. easy conversion, because INT is in mysql? The timestamp is saved. You do not need to convert the format. Otherwise, the time in PHP and mysql is different, and the access needs to be converted.
If inT is used, the database does not need to be moved? Php.
3. convenient time calculation. The advantage of unix time is that it is calculated by example.