#使用视图获取多表中的数据
DROP VIEW IF EXISTS `view_result`;
CREATE VIEW `view_result`
AS
SELECT s.`studentName` 学生姓名, su.`subjectName` 课程名,AVG(`studentResult`) 平均成绩 FROM `result` r
INNER JOIN `student` s ON s.`studentNo`=r.`studentNo`
INNER JOIN `subject` su ON su.`subjectNo`=r.`subjectNo`
GROUP BY s.`studentName`,su.`subjectName`;
SELECT * FROM view_result;
SELECT * FROM result;
#使用mysqldump命令将myschool数据库中的学生表,成绩表备份到文件d:\ex\myschool_xxxxx.sql中
mysqldump -uroot -proot myschool student result > d:\ex\myschool_20170926.sql
#使用mysql命令和source命令两种方式还原学生表,成绩表到school数据库 DROP DATABASE IF EXISTS `schoolDB`; CREATE DATABASE `schoolDB`; #使用mysql命令 mysql -u root -proot schoolDB < d:\ex\myschool_20170926.sql
#使用source命令 source d:\ex\myschool_20170926.sql;
#使用SELECT....INTO outfile语句到处科目表subject中的记录
SELECT * FROM `subject` INTO OUTFILE 'd:/ex/subject_out.txt';
#使用load data infile语句导入subject_out.txt数据到schoolDB数据库
USE myschooldb;
#创建subject表结构
CREATE TABLE `subject` (
`subjectNo` INT(4) NOT NULL AUTO_INCREMENT COMMENT '课程编号',
`subjectName` VARCHAR(50) DEFAULT NULL COMMENT '课程名称',
`classHour` INT(4) DEFAULT NULL COMMENT '学时',
`gradeID` INT(4) DEFAULT NULL COMMENT '年级编号',
PRIMARY KEY (`subjectNo`)
) ENGINE=INNODB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8 COMMENT='科目表';
#导入数据
LOAD DATA INFILE 'd:/ex/subject_out.txt' INTO TABLE `subject`;