Can Autoincrement be null?

Question

When you insert a new record to the table (or upon adding an AUTO_INCREMENT attribute with the ALTER TABLE statement), and the auto_increment field is NULL or DEFAULT (in the case of an INSERT), the value will automatically be incremented. This also applies to 0, unless the NO_AUTO_VALUE_ON_ZERO SQL_MODE is enabled.

Does auto increment need not NULL?

You don't have to specify NOT NULL on the column definition with AUTO_INCREMENT . You can leave it off, and MySQL will make the column NOT NULL . And if you specify NULL in place of NOT NULL , MySQL will accept the syntax, but it will ignore that, and make the column NOT NULL anyway.

How do I set Autoincrement to zero?

How To Reset MySQL Autoincrement Column1Directly Reset Autoincrement Value. Alter table syntax provides a way to reset autoincrement column. ... 2Truncate Table. Truncate table automatically reset the Autoincrement values to 0. ... 3Drop & Recreate Table. This is another way of reseting autoincrement index.

Is Autoincrement primary key?

Auto-increment allows a unique number to be generated automatically when a new record is inserted into a table. Often this is the primary key field that we would like to be created automatically every time a new record is inserted.

Does MySQL auto increment start at 0?

By default, the AUTO_INCREMENT column begins at 1. You can also explicitly assign 0 to the column to generate the next sequence number unless the NO_AUTO_VALUE_ON_ZERO SQL mode is enabled. Assigning NULL to the column will also generate the next sequence number, as long as the column was declared NOT NULL.

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