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Navicat、Pycharm連接Mysql

本文轉載自   查看原文   2019-08-22 21:33   375 

一、Navicat使用

鏈接：https://pan.baidu.com/s/15SEMLk-oUSZgGRi6JJAEdA
提取碼：m9ra
下載后，將破解補丁放入你Navicat的安裝目錄，就破解成功了。

1.進入后點擊“連接”

2.點擊“MySQL”

 

3.連接名可以選填，端口號填寫3306，用戶名root，如果你設置了密碼，就填寫你設置的密碼，如果沒有直接跳過。

二、查詢練習

導入sql語句代碼：

/*
 數據導入：
 Navicat Premium Data Transfer

 Source Server         : localhost
 Source Server Type    : MySQL
 Source Server Version : 50624
 Source Host           : localhost
 Source Database       : sqlexam

 Target Server Type    : MySQL
 Target Server Version : 50624
 File Encoding         : utf-8

 Date: 10/21/2016 06:46:46 AM
*/

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;
sql語句

1.拷貝上述代碼，新建一個.sql文件，保存到桌面

2.打開navicat新建數據庫day41，選中新建的數據庫鼠標右鍵選擇運行SQL文件

3.彈出文件框，選中剛剛保存到桌面的.sql文件即可

練習題：

'''
1、查詢所有的課程的名稱以及對應的任課老師姓名
2、查詢平均成績大於八十分的同學的姓名和平均成績
3、 查詢沒有報李平老師課的學生姓名
4、 查詢沒有同時選修物理課程和體育課程的學生姓名
5、 查詢掛科超過兩門(包括兩門)的學生姓名和班級
'''

參考答案：

#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
    teacher
    INNER JOIN course 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,
    t1.平均成績 
FROM
    student
    INNER JOIN ( SELECT student_id, avg( num ) AS 平均成績 FROM score GROUP BY student_id HAVING avg( num ) > 80 ) AS t1 ON student.sid = t1.student_id

#3.查詢沒有報李平老師課的學生姓名
select student.sname from student where student.sid not in
(
SELECT DISTINCT
    student_id
FROM
    score  
WHERE
    score.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.查詢沒有同時選修物理課程和體育課程的學生姓名
SELECT
    student.sname 
FROM
    student 
WHERE
    student.sid IN (
SELECT
    score.student_id 
FROM
    score
    INNER JOIN course ON score.course_id = course.cid 
WHERE
    cname IN ( '物理', '體育' ) 
GROUP BY
    student_id 
HAVING
    count( course_id ) < 2 
    )

#5.查詢掛科超過兩門的（包括兩門）的學生姓名和班級
SELECT
    student.sname,
    class.caption 
FROM
    student
    INNER JOIN class ON student.class_id = class.cid 
WHERE
    student.sid IN ( SELECT student_id FROM score WHERE num < 60 GROUP BY student_id HAVING count( course_id ) >= 2 )
參考答案

三、python中的pymysql模塊

#1.安裝：pymysql

#2.代碼連接
import pymysql
#鏈接
conn = pymysql.connect(
    host = '127.0.0.1',
    port = 3306,
    user = 'root',
    password = '123',
    database = 'day38',
    charset = 'utf8'
)
#cursor = conn.cursor() 默認是返回一個元組
cursor = conn.cursor(pymysql.cursors.DictCursor) # 產生一個游標對象，以字典的形式返回查詢出來的數據
鍵是表的字段 值是表的字段對應的信息
sql = 'select * from teacher'
cursor.execute(sql) # 執行傳入的sql語句
# print(cursor.execute(sql)) 執行語句返回的是數據條數
print(cursor.fetchone()) # 只獲取一條數據
print(cursor.fetchone())
print(cursor.fetchone())
cursor.scroll(1,'absolute') # 控制光標移動 absolute相對於起始位置往后移動幾位
cursor.scroll(2,'relative') # relative相對於當前位置 往后移動幾位
print(cursor.fetchall()) # 獲取所有數據 返回的結果是一個列表

四、注入問題

# 記住不要手動去拼接查詢的sql語句
username = input('username>>>:').strip()
password = input('password>>>:').strip()

# 錯誤！會導致注入問題！
sql = "select * from user where name = ’%s‘ and password = ’%s‘“%(username,password) 

#注入問題 導致的現象：
username>>>: jason' -- asdakjshdkjsds

#不知道用戶名和密碼的情況下：
username>>> xxx' or 1=1 --askjfkjhfjaljfha
password = ''

#正確操作
cursor.execute(sql,(username,password)) #能夠自動幫你過濾特殊符號， 避免sql注入問題

五、增刪改

#增
sql = 'insert into user values("jerry","666")'

cursor.execute(sql)

conn.commit()

#改
sql = 'update user set password = "456"'

cursor.execute(sql)

conn.commit()

#刪

sql = "delete from user where name ='jerry'"

cursor.execute(sql)

conn.commit()

 


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