How to add and delete columns in mysql

This article introduces the relevant knowledge of "how to add and delete columns in mysql". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

-- add columns

CREATE TABLE register (

Id INT PRIMARY KEY AUTO_INCREMENT

-- name VARCHAR (10) DEFAULT NULL UNIQUE KEY

RegisTime TIMESTAMP DEFAULT CURRENT_TIMESTAMP ()

Fund DOUBLE (9,2) DEFAULT 1000000.00

-tel CHAR (11) NOT NULL

)

ALTER TABLE register ADD tel CHAR (11) NOT NUL

ALTER TABLE register ADD name VARCHAR (10) DEFAULT NULL UNIQUE KEY AFTER id

ALTER TABLE register ADD tel CHAR (11) NOT NULL,ADD name VARCHAR (10) DEFAULT NULL UNIQUE KEY AFTER id

-- delete a single column

ALTER TABLE register DROP name

-- delete multiple columns

ALTER TABLE register DROP fund,DROP tel

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