How to add, delete and modify columns in MySQL database

This article uses an example to describe how to add, delete, and modify columns in a MySQL database. Share with you for your reference, the details are as follows:

Create a new table user_info:

CREATE TABLE user_info(
id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
username CHAR(20) NOT NULL DEFAULT '',
gender TINYINT UNSIGNED NOT NULL DEFAULT 0,
weight TINYINT UNSIGNED NOT NULL DEFAULT 0
)ENGINE=MyISAM DEFAULT CHARSET=utf8;

The new column is the last column of the table by default.

Syntax: alter table table name add column name column type column attribute

alter table user_info add height tinyint unsigned not null default 0;

Deleting a column

Syntax: alter table table name drop column name

alter table user_info drop height;

Add a column and put it after the specified column

Syntax: alter table table name add column name type attribute [default value] after specify column name

alter table user_info add height tinyint not null default 0 after username;

Modify the specified column name

Syntax: alter table table name change old column name new column name type attribute default value

alter table user_info change height shengao smallint not null default 0;

modify Modify the column, but cannot modify the column name

Syntax: alter table table name modify column name type attribute default value

alter table user_info modify shengao tinyint not null default 0;

Readers who are interested in more MySQL-related content can check out the following topics: "Summary of MySQL Common Functions", "Summary of MySQL Log Operation Skills", "Summary of MySQL Transaction Operation Skills", "Summary of MySQL Stored Procedure Skills" and "Summary of MySQL Database Lock-Related Skills".

I hope this article will be helpful to everyone's MySQL database design.