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How to add fields in mysql

藏色散人
藏色散人 Original
2019-05-10 13:37:16 63684browse

Mysql method of adding fields: [create table id_name(id int, name varchar(20));], which means adding id and name fields.

How to add fields in mysql

mysql adds two fields:

(recommended tutorial:mysql video tutorial)

mysql> create table id_name(id int,name varchar(20)); Query OK, 0 rows affected (0.13 sec) mysql> alter table id_name add age int,add address varchar(11); Query OK, 0 rows affected (0.13 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc id_name; +---------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------+-------------+------+-----+---------+-------+ | id | int(11) | YES | | NULL | | | name | varchar(20) | YES | | NULL | | | age | int(11) | YES | | NULL | | | address | varchar(11) | YES | | NULL | | +---------+-------------+------+-----+---------+-------+ 4 rows in set (0.00 sec)

mysqlAdd a field:

alter table user add COLUMN new1 VARCHAR(20) DEFAULT NULL; //增加一个字段,默认为空 alter table user add COLUMN new2 VARCHAR(20) NOT NULL; //增加一个字段,默认不能为空

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