MySQL视图表创建与修改

MySQL视图表创建与修改

1、创建

CREATE [OR REPLACE] [<algorithm attributes>] VIEW [database.]< name> [(<columns>)]
AS <select statement> [<check options>]
例子：

CREATE VIEW `view_articles`
AS
SELECT
    a.id AS id,
    a.title AS title,
    a.content AS content,
    t.name AS tagname,
    u.firstname AS "username"
FROM `articles` a
    LEFT JOIN `tags` t
        ON a.tag_id = t.id
    LEFT JOIN `users` u
        ON a.user_id = u.id
ORDER BY a.posttime DESC;
修改

ALTER [<algorithm attributes>] VIEW [<database>.]< name> [(<columns>)]
AS<select statement> [<check options>]
例子：

ALTER VIEW `view_articles`
AS
SELECT
    a.id AS id,
    a.title AS title,
    a.content AS content,
    a.posttime AS posttime,
    t.name AS tagname,
    CONCAT(u.firstname,' ',u.lastname) AS "username"
FROM `articles` a
    LEFT JOIN `tags` t
        ON a.tag_id = t.id
    LEFT JOIN `users` u
        ON a.user_id = u.id
ORDER BY a.posttime DESC;

修改已经建立好的视图表，最简单的方法就是在phpMyAdmin导出视图表的SQL，然后修改开头的“CREATE”（后面的”ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER”等不用管，保留它）为”ALTER”，运行语句即可。