mysql如何增加字段

mysql增加字段的方法:【create table id_name(id int,name varchar(20));】,表示增加id和name字段。

mysql如何增加字段

mysql增加兩個字段:

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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)

mysql增加一個字段:

alter?table?user?add?COLUMN?new1?VARCHAR(20)?DEFAULT?NULL;?//增加一個字段,默認為空 alter?table?user?add?COLUMN?new2?VARCHAR(20)?NOT?NULL;??//增加一個字段,默認不能為空

以上就是

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