In fact, this m has nothing to do with the range that an INT can represent. As long as you choose an INT, it is represented by 4 bytes, 1 byte and 8 bits. If an unsigned number is represented, the range that can be represented is 0-232- 1, and any number within this range can be stored.

However, this does not mean that it has nothing to do with the presentation. There is a zerofll in mysql. When you choose 0 to fill in the form, the storage will be very different. At this time, if int(4) is selected and 12 is stored, the database will store 0 12. If 12345 is filled in, it will be stored as it is.