MySQL DatabaseLesson 60Free preview

MySQL Auto Increment

This lesson is part of MySQL · All levels

Summary

AUTO_INCREMENT automatically adds a column of value every time a new line is inserted, so you don't have to fill in the ID manually. These columns are usually paired with a primary key of the type INT or BIGINT. The next value is usually taken from the largest value ever used so it is not reused.

Key points

AUTO_INCREMENT can only be used in one column per table and must be indexed (e.g. PRIMARY KEY)
When INSERT does not mention this column, the value is filled automatically
The initial value can be set with the AUTO_INCREMENT = n option when CREATE TABLE
The value used once is not recalculated even if the last line is deleted
AUTO_INCREMENT applies to numerical types such as INT and BIGINT

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