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How do I make a column auto increment in mysql?
Syntax. In MySQL, the syntax to change the starting value for an AUTO_INCREMENT column using the ALTER TABLE statement is: ALTER TABLE table_name AUTO_INCREMENT = start_value; table_name.
How does auto increment work in mysql?
Auto Increment is a function that operates on numeric data types. It automatically generates sequential numeric values every time that a record is inserted into a table for a field defined as auto increment.
Where to set auto increment value in InnoDB?
To start with an AUTO_INCREMENT value other than 1, set that value with CREATE TABLE or ALTER TABLE , like this: For information about AUTO_INCREMENT usage specific to InnoDB, see AUTO_INCREMENT Handling in InnoDB . For MyISAM tables, you can specify AUTO_INCREMENT on a secondary column in a multiple-column index.
When do you use auto increment in MySQL?
In this case (when the AUTO_INCREMENT column is part of a multiple-column index), AUTO_INCREMENT values are reused if you delete the row with the biggest AUTO_INCREMENT value in any group. This happens even for MyISAM tables, for which AUTO_INCREMENT values normally are not reused.
How is auto increment calculated in MyISAM table?
For MyISAM tables, you can specify AUTO_INCREMENT on a secondary column in a multiple-column index. In this case, the generated value for the AUTO_INCREMENT column is calculated as MAX (auto_increment_column) + 1 WHERE prefix=given-prefix . This is useful when you want to put data into ordered groups.
How to use auto increment in table animals?
The AUTO_INCREMENT attribute can be used to generate a unique identity for new rows: CREATE TABLE animals ( id MEDIUMINT NOT NULL AUTO_INCREMENT, name CHAR(30) NOT NULL, PRIMARY KEY (id) ); INSERT INTO animals (name) VALUES (‘dog’),(‘cat’),(‘penguin’), (‘lax’),(‘whale’),(‘ostrich’); SELECT * FROM animals;