What is the difference between SERIAL and AUTO_INCREMENT in mysql

Question

I have come across two ways to increment the ids in mysql automatically.

One is SERIAL and other is AUTOINCREMENT.

So Suppo

Answer 1

AUTO_INCREMENT is an attribute of a specific column of any numeric type (int or float), both signed and unsigned. When rows are inserted it automatically assigns sequential numbers, so you don't have to (e.g. by using LAST_INSERT_ID()). See http://dev.mysql.com/doc/refman/5.0/en/example-auto-increment.html

SERIAL is an alias that combines column type casting (BIGINT specifically), AUTO_INCREMENT, UNSIGNED and other attributes for a specific column (see quote from docs below). See https://dev.mysql.com/doc/refman/8.0/en/numeric-type-syntax.html

SERIAL is an alias for BIGINT UNSIGNED NOT NULL AUTO_INCREMENT UNIQUE.

SERIAL DEFAULT VALUE in the definition of an integer column is an alias for NOT NULL AUTO_INCREMENT UNIQUE.