How to solve mysql modification

About how mysql modifies ALTERTABLEpre_forum_attachmentCHANGE 'aid ''aid 'mediumint (8) unsignedNOTNULLAUTO_INCREMENT, the error message is # 1264-Outofrangevalue about mysql modification.
Alter table pre_forum_attachment CHANGE 'aid ''' mediumint (8) unsigned not null AUTO_INCREMENT
The error is #1264-Out of range value adjusted for column 'aid 'at row 3.


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Bigint
Integer data from-2 ^ 63 (-9223372036854775808) to 2 ^ 63-1 (9223372036854775807) (all numbers ). The storage size is 8 bytes.

Mediumint
The signed range is-8388608 to 8388607, the unsigned range is 0 to 16777215, and 3 bytes are used.
The unsigned range is 0 to 16777215.

Because the storage range of mediumint is much smaller than that of bigint, it will inevitably cause overflow.
The primary key must be unique.
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The boss explained it clearly. In fact, your English prompt is also very clear.