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文章目錄
1、navicat使用說明
（1）navicat連接雲上數據庫
先建立ssh連接到雲主機上：
（2）navicat簡單使用
其他功能自己慢慢摸索吧！！
2、準備表
注意：下面表的生成，需要用到navicat工具！navicat就是一個數據庫的可視化工具。讓你不用再寫複雜的SQL語句，只是鼠標點點點，實現各種數據庫的騷操作！
導出的sql語句代碼：
SET NAMES utf8;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for `class`
-- ----------------------------
DROP TABLE IF EXISTS `class`;
CREATE TABLE `class` (
`cid` int(11) NOT NULL AUTO_INCREMENT,
`caption` varchar(32) NOT NULL,
PRIMARY KEY (`cid`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of `class`
-- ----------------------------
BEGIN;
INSERT INTO `class` VALUES ('1', '三年二班'), ('2', '三年三班'), ('3', '一年二班'), ('4', '二年九班');
COMMIT;
-- ----------------------------
-- Table structure for `course`
-- ----------------------------
DROP TABLE IF EXISTS `course`;
CREATE TABLE `course` (
`cid` int(11) NOT NULL AUTO_INCREMENT,
`cname` varchar(32) NOT NULL,
`teacher_id` int(11) NOT NULL,
PRIMARY KEY (`cid`),
KEY `fk_course_teacher` (`teacher_id`),
CONSTRAINT `fk_course_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teacher` (`tid`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of `course`
-- ----------------------------
BEGIN;
INSERT INTO `course` VALUES ('1', '生物', '1'), ('2', '物理', '2'), ('3', '體育', '3'), ('4', '美術', '2');
COMMIT;
-- ----------------------------
-- Table structure for `score`
-- ----------------------------
DROP TABLE IF EXISTS `score`;
CREATE TABLE `score` (
`sid` int(11) NOT NULL AUTO_INCREMENT,
`student_id` int(11) NOT NULL,
`course_id` int(11) NOT NULL,
`num` int(11) NOT NULL,
PRIMARY KEY (`sid`),
KEY `fk_score_student` (`student_id`),
KEY `fk_score_course` (`course_id`),
CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`),
CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`)
) ENGINE=InnoDB AUTO_INCREMENT=53 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of `score`
-- ----------------------------
BEGIN;
INSERT INTO `score` VALUES ('1', '1', '1', '10'), ('2', '1', '2', '9'), ('5', '1', '4', '66'), ('6', '2', '1', '8'), ('8', '2', '3', '68'), ('9', '2', '4', '99'), ('10', '3', '1', '77'), ('11', '3', '2', '66'), ('12', '3', '3', '87'), ('13', '3', '4', '99'), ('14', '4', '1', '79'), ('15', '4', '2', '11'), ('16', '4', '3', '67'), ('17', '4', '4', '100'), ('18', '5', '1', '79'), ('19', '5', '2', '11'), ('20', '5', '3', '67'), ('21', '5', '4', '100'), ('22', '6', '1', '9'), ('23', '6', '2', '100'), ('24', '6', '3', '67'), ('25', '6', '4', '100'), ('26', '7', '1', '9'), ('27', '7', '2', '100'), ('28', '7', '3', '67'), ('29', '7', '4', '88'), ('30', '8', '1', '9'), ('31', '8', '2', '100'), ('32', '8', '3', '67'), ('33', '8', '4', '88'), ('34', '9', '1', '91'), ('35', '9', '2', '88'), ('36', '9', '3', '67'), ('37', '9', '4', '22'), ('38', '10', '1', '90'), ('39', '10', '2', '77'), ('40', '10', '3', '43'), ('41', '10', '4', '87'), ('42', '11', '1', '90'), ('43', '11', '2', '77'), ('44', '11', '3', '43'), ('45', '11', '4', '87'), ('46', '12', '1', '90'), ('47', '12', '2', '77'), ('48', '12', '3', '43'), ('49', '12', '4', '87'), ('52', '13', '3', '87');
COMMIT;
-- ----------------------------
-- Table structure for `student`
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
`sid` int(11) NOT NULL AUTO_INCREMENT,
`gender` char(1) NOT NULL,
`class_id` int(11) NOT NULL,
`sname` varchar(32) NOT NULL,
PRIMARY KEY (`sid`),
KEY `fk_class` (`class_id`),
CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`)
) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of `student`
-- ----------------------------
BEGIN;
INSERT INTO `student` VALUES ('1', '男', '1', '理解'), ('2', '女', '1', '鋼蛋'), ('3', '男', '1', '張三'), ('4', '男', '1', '張一'), ('5', '女', '1', '張二'), ('6', '男', '1', '張四'), ('7', '女', '2', '鐵錘'), ('8', '男', '2', '李三'), ('9', '男', '2', '李一'), ('10', '女', '2', '李二'), ('11', '男', '2', '李四'), ('12', '女', '3', '如花'), ('13', '男', '3', '劉三'), ('14', '男', '3', '劉一'), ('15', '女', '3', '劉二'), ('16', '男', '3', '劉四');
COMMIT;
-- ----------------------------
-- Table structure for `teacher`
-- ----------------------------
DROP TABLE IF EXISTS `teacher`;
CREATE TABLE `teacher` (
`tid` int(11) NOT NULL AUTO_INCREMENT,
`tname` varchar(32) NOT NULL,
PRIMARY KEY (`tid`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of `teacher`
-- ----------------------------
BEGIN;
INSERT INTO `teacher` VALUES ('1', '張磊老師'), ('2', '李平老師'), ('3', '劉海燕老師'), ('4', '朱雲海老師'), ('5', '李傑老師');
COMMIT;
SET FOREIGN_KEY_CHECKS = 1;
拷貝上述代碼，新建一個.sql文件，保存到桌面
打開navicat新建數據庫db1，選中新建的數據庫鼠標右鍵選擇運行SQL文件
彈出文件框，選中剛剛保存到桌面的.sql文件即可
運行完上述sql文件就會生成以下幾個表：
3、模型圖
4、查詢題目
（1）查詢所有的課程的名稱以及對應的任課老師姓名
SELECT
course.cname,
teacher.tname
FROM
course
INNER JOIN teacher ON course.teacher_id = teacher.tid
（2）查詢平均成績大於八十分的同學的姓名和平均成績
SELECT
student.sname,
AVG(score.num)
FROM
student
INNER JOIN score ON student.sid = score.student_id
GROUP BY student.sid
HAVING AVG(score.num) > 80;
（3）查詢沒有報李平老師課的學生姓名
1. 選出李平老師所教的課程的課程號
SELECT
course.cid
FROM
course
INNER JOIN teacher ON course.teacher_id = teacher.tid
WHERE
teacher.tname = '李平老師'
2. 根據李平老師所教的課程的課程號，找出報李平老師課的學生id
SELECT DISTINCT
student_id
FROM
score
WHERE
course_id IN (
SELECT
course.cid
FROM
course
INNER JOIN teacher ON course.teacher_id = teacher.tid
WHERE
teacher.tname = ‘李平老師‘
)
3. 根據得到的報李平老師課的學生id，取反得到沒報李平老師課的學生id，並根據查詢其名字
SELECT
student.sname
FROM
student
WHERE
sid NOT IN (
SELECT DISTINCT
student_id
FROM
score
WHERE
course_id IN (
SELECT
course.cid
FROM
course
INNER JOIN teacher ON course.teacher_id = teacher.tid
WHERE
teacher.tname = ‘李平老師‘
)
);
（4）查詢同時選修物理課程和體育課程的學生姓名
1. 查詢出'體育'、'物理'兩門課程的課程號
SELECT
cid
FROM
course
WHERE
cname = '物理' OR cname = '體育'
2. 過濾出選修這兩門課程最少其中一門的所有人，然後按學號分組，count計數，把count計數等於2的學生號選出來
SELECT
student_id
FROM
score
WHERE
course_id IN (
SELECT
cid
FROM
course
WHERE
cname = '物理'
OR cname = '體育'
)
GROUP BY
student_id
HAVING
COUNT(course_id) = 2
3. 根據學生號查詢學生姓名
SELECT
student.sname
FROM
student
WHERE
sid IN (
SELECT
student_id
FROM
score
WHERE
course_id IN (
SELECT
cid
FROM
course
WHERE
cname = '物理'
OR cname = '體育'
)
GROUP BY
student_id
HAVING
COUNT(course_id) = 2
);
（5）查詢掛科超過兩門(包括兩門)的學生姓名和班級名
注意：caption字段裏面存的就是班級名！
# 兩次內連接
1. 先把掛科兩門及以上的學生的姓名和班級名選出來
SELECT
student.sname,
student.class_id
FROM
student INNER JOIN score ON student.sid = score.student_id
WHERE
score.num < 60 GROUP BY score.student_id HAVING COUNT( score.student_id ) >= 2
2. 把上面得到的掛科學生姓名與班級名的表取別名爲t1，然後將class和t1進行內連接，然後取得sname和caption
SELECT
t1.sname,
class.caption
FROM
class
INNER JOIN (
SELECT
student.sname,
student.class_id
FROM
student INNER JOIN score ON student.sid = score.student_id
WHERE
score.num < 60 GROUP BY score.student_id HAVING COUNT( score.student_id ) >= 2
) AS t1 ON t1.class_id = class.cid;
# 內連接+子查詢
# 比上面簡單一點的方法
SELECT
student.sname,
class.caption
FROM
class
INNER JOIN student ON class.cid = student.class_id
WHERE
student.sid IN ( SELECT student_id FROM score WHERE num < 60 GROUP BY student_id HAVING COUNT( course_id ) >= 2 );