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mysql 表维护与改造代码分享

WBOY
WBOYOriginal
2016-06-07 17:55:091079browse

当数据库中表的数量比较多时,不利于维护,本文将以此问题进行详细介绍如何维护mysql表,与如何修改mysql表

改变列的数据类型
[sql]
ALTER TABLE visitor MODIFY nam VARCHAR(30);
追加新列
[sql]
ALTER TABLE visitor ADD age INT;
ALTER TABLE visitor ADD age INT FIRST;
ALTER TABLE visitor ADD age INT AFTER nam;
改变列的位置
[sql]
ALTER TABLE visitor MODIFY age INT AFTER nam;
改变列名 和 类型
[sql]
ALTER TABLE visitor CHANGE birth birthday DATE;
删除列
[sql]
ALTER TABLE visitor DROP age;
表的复制
[sql]
CREATE TABLE customerH SELECT * FROM customer;
CREATE TABLE customerG LIKE customer;
INSERT INTO customerG SELECT * FROM customer;
INSERT INTO tb1G(no) SELECT bang FROM tb1;
表的删除
[sql]
DROP TABLE IF EXISTS customerG;
DROP TABLE customerG;
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