sql add auto increment id to existing table code example

Example 1: sql query to make a existing column auto increment

Alter table table_name modify column_name datatype(length) AUTO_INCREMENT PRIMARY KEY

Example 2: how to auto increment in sql

CREATE TABLE Persons (
    Personid int NOT NULL AUTO_INCREMENT,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    PRIMARY KEY (Personid)
);
INSERT INTO Persons (FirstName,LastName)
VALUES ('Lars','Monsen');

Example 3: how to alter auto increment in sql

INSERT INTO Persons (Personid,FirstName,LastName)

VALUES (seq_person.nextval,'Lars','Monsen');

Example 4: mysql add auto increment id existing table

ALTER TABLE `users` ADD `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY

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Sql Example