一、視圖實例1-創(chuàng)建視圖及查詢數(shù)據(jù)操作

首先，創(chuàng)建三個表：user、course、user_course

表：user

CREATE TABLE `user` (`id` int(11) NOT NULL AUTO_INCREMENT,`account` varchar(200) NOT NULL,`name` varchar(200) NOT NULL,`address` varchar(500) DEFAULT NULL,`others` varchar(500) DEFAULT NULL,`others2` varchar(500) DEFAULT NULL,PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8; insert into user (account,name,address,others1,others2)
values (user1,'小張','天津',1,1), (user2,'小王','北京',2,2), (user3,'小李','上海',3,3);

表：course

CREATE TABLE `course` (`id` int(11) NOT NULL AUTO_INCREMENT,`name` varchar(200) NOT NULL,`description` varchar(500) NOT NULL,PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8; insert into course (name,description) values ('JAVA','JAVA課程'), ('C++','C++課程'), ('C','C課程');

表：user_course

CREATE TABLE `user_course` (`id` bigint(20) NOT NULL AUTO_INCREMENT,`userid` bigint(20) NOT NULL,`courseid` bigint(20) NOT NULL,PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8; insert into user_course (userid,courseid) values (1,2), (1,3), (2,4), (3,5);

其次，利用表關(guān)聯(lián)三表進(jìn)行聯(lián)合查詢：

SELECTuc.id AS id,u. NAME AS username,c.description AS coursename FROMUSER u LEFT JOIN user_course uc ON ((u.id = uc.userid)) LEFT JOIN course c ON ((uc.courseid = c.id)) WHEREu. NAME = '小王';

最后，創(chuàng)建視圖進(jìn)行三表關(guān)聯(lián)查詢：

DROP VIEW IF EXISTS view_user_course;CREATE VIEW view_user_course AS (SELECTuc.id AS id,u. NAME AS username,c.description AS coursenameFROMUSER uLEFT JOIN user_course uc ON ((u.id = uc.userid))LEFT JOIN course c ON ((uc.courseid = c.id)) ); SELECT* FROMview_user_course vuc WHEREvuc.username = '小張';

二、視圖實例2-增刪改數(shù)據(jù)操作

首先， 創(chuàng)建視圖：

視圖與表是一對一關(guān)系情況：如果沒有其它約束（如視圖中沒有的字段，在基本表中是必填字段情況），是可以進(jìn)行增刪改數(shù)據(jù)操作；

create view st_view as( select u.id as st_id, u.`name` as st_name, u.account as st_user from `user` u ); #視圖增刪改查 insert into st_view (st_name,st_user) values('小孫','user4');delete from st_view where st_name = '小孫';update st_view set st_name = '小田' where st_id = 7

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轉(zhuǎn)載于:https://www.cnblogs.com/Owen-ET/p/8710414.html

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