mysql 表維護(hù)與改造代碼分享

當(dāng)數(shù)據(jù)庫(kù)中表的數(shù)量比較多時(shí)，不利于維護(hù)，本文將以此問(wèn)題進(jìn)行詳細(xì)介紹如何維護(hù)mysql表，與如何修改mysql表

改變列的數(shù)據(jù)類(lèi)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;
改變列的位置
[sql]
ALTER TABLE visitor MODIFY age INT AFTER nam;
改變列名 和 類(lèi)型
[sql]
ALTER TABLE visitor CHANGE birth birthday DATE;
刪除列
[sql]
ALTER TABLE visitor DROP age;
表的復(fù)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;
表的刪除
[sql]
DROP TABLE IF EXISTS customerG;
DROP TABLE customerG;