If you would like this value to start at an integer other than 1, you could do so by altering the table rule: ALTER TABLE member AUTO_INCREMENT = 100 MySQL knows that this is the primary key field and will auto-generate a new, unique ID for each record created.īy default, the first record created will start with a value of 1 for the id column, followed by 2, 3, and so on, climbing sequentially until the maximum value has been reached for the column's set data type. Since the id column's value is auto-generated, we don't need to set a value manually for it. We'll start by creating a new member table containing an id field with the AUTO_INCREMENT keyword and PRIMARY KEY constraint, along with some data about each member: CREATE TABLE member ( id BIGINT NOT NULL AUTO_INCREMENT, first_name VARCHAR(50) NOT NULL, last_name VARCHAR(50) NOT NULL, PRIMARY KEY (id) ) Īnd insert some data into the table: INSERT INTO member (first_name, last_name) VALUES ('Josh', 'Rowe') The PRIMARY KEY constraint assigned to a table field is what gives the identifier its uniqueness, and is also a requirement for auto-increment fields.Įach table can only have a single primary key and, just like auto-increment fields, primary keys cannot have DEFAULT values and cannot contain NULL values. This is a primary key field whose value is automatically generated each time a new record is created, removing the requirement of executing multiple queries to determine the latest identifier and running a calculation for the new identifier.Īn auto-increment field is always an integer type, cannot have a DEFAULT value assigned to it, and must be NOT NULL. What is Auto-Increment in MySQL?Īuto-increment provides a unique identifier for a newly inserted record in a MySQL database table using the AUTO_INCREMENT keyword. Let's dive into the details of each, then we'll get into some code. In this tutorial, you'll learn how auto-increment works with primary keys and how to utilize them when working with MySQL database tables.
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