MySQL学生成绩管理系统based on C++ and Clion

mysql_free_result()函数的作用是释放结果集的内存，是同步的，也就是要中断一下

该实验使用了MySQL链接数据库的基本使用方法，具体使用了

MYSQL_RES 数据库的mysql_store_result()函数的返回值是一个结果集，该函数的作用是检索比并存储整个结果集

MYSQL_ROW 数据库的mysql_fetch_row()函数的返回值是一个集行，搭配上一个mysql_res使用的，一个一个读他，函数的作用是获取下一个结果集行

mysql_query()函数是执行语句的意思，也就是发给数据库让他执行这条语句，函数传递语句的使用如果是std::string 类型的话，需要调用.c_str()函数进行转化成字符才能进行传递

std::ifstream  infile("../src/student2.txt",std::ios::in);
infile>>temp[j];

std::ofstream outfile("../src/student2.txt",std::ios::out);
outfile<<"学号\t"<<"名字\t"<<"得分\n"<<std::endl;

该方法分别对应了流对于文件的读入和写入操作的执行，使用完毕之后要执行close()操作

本实验我认为最重要的是对于mysql的链接建立问题

    MYSQL mysql;
    const char db_Username[]="root";
    const char db_Password[]="123456";
    const char db_Host[]="localhost";
    const char db_Name[]="sp";
    unsigned long db_Port=3306;
    mysql_init(&mysql);
    mysql_options(&mysql,MYSQL_SET_CHARSET_NAME,"gbk");
    if(mysql_real_connect(&mysql,db_Host,db_Username,db_Password,db_Name,db_Port,NULL,0)==NULL){
        std::cout<<"connect error!!!"<<std::endl;
        return false;
    }
    std::cout<<"connect success!!!"<<std::endl;

1. build
2. docs
3. include
   1. Main.h
   2. Student.h
4. src
   1. main.cpp
   2. Methods.cpp
   3. student.cpp
   4. student2.txt
5. CMakeLists.txt

Main.h

#ifndef NEW_PROJECTS_MAIN_H
#define NEW_PROJECTS_MAIN_H

#include<iostream>
#include<mysql.h>
#include <fstream>





void show_mean();//显示菜单

bool connect_mysql(MYSQL& mysql);//链接数据库

void query(MYSQL& mysql);//查询学生数据

void modify(MYSQL& mysql);//修改学生数据

void insert(MYSQL& mysql);//添加学生数据

void Delete(MYSQL& mysql);//删除学生数据

void filein(MYSQL& mysql);//导入文件数据

int getline();//获取文件行数

void fileout(MYSQL& mysql);//将数据库中的文件导出到另外一个文件中

void createTable(MYSQL& mysql);//创建表格

#endif //NEW_PROJECTS_MAIN_H

Student.h

#ifndef NEW_PROJECTS_STUDENT_H
#define NEW_PROJECTS_STUDENT_H
#include"main.h"
class Student{
private:
    int Id;
    std::string name;
    int score;
public:
    int getId();
    std::string getName();
    int getScore();
    void setId(int& Id);
    void setName(std::string& name);
    void setScore(int& score);
};
#endif //NEW_PROJECTS_STUDENT_H

main.cpp

#include "Main.h"

int main() {
    MYSQL mysql;
    mysql_init(&mysql);
    mysql_options(&mysql,MYSQL_SET_CHARSET_NAME,"gbk");
    system("chcp 65001");
    if(connect_mysql(mysql)==false){
        return 0;
    }
    else{
        int choices=1;
        while(choices!=0){
            show_mean();
            std::cin>>choices;
            switch (choices) {
                case 1:
                    filein(mysql);
                    break;
                case 2:
                    query(mysql);
                    break;
                case 3:
                    modify(mysql);
                    break;
                case 4:
                    insert(mysql);
                    break;
                case 5:
                    Delete(mysql);
                    break;
                case 0:
                    fileout(mysql);
                    break;
                default:
                    std::cout<<"Input error,please again!!!"<<std::endl;
                    break;
            }
        }
        std::cout<<"success"<<std::endl;
        system("pause");
        system("cls");
    }

}

Methods.cpp

#include"Main.h"
#include"Student.h"
void show_mean() // 展示功能菜单并让用户选择功能
{



    std::cout << std::endl << "=========================================欢迎使用学生管理系统========================================" << std::endl << std::endl;;
    std::cout << "请选择您要进行的操作" << std::endl;

    std::cout << "\t 1. 读取学生数据并显示" << std::endl;
    std::cout << "\t 2. 查询学生数据" << std::endl;
    std::cout << "\t 3. 修改学生数据" << std::endl;
    std::cout << "\t 4. 添加学生数据" << std::endl;
    std::cout << "\t 5. 删除学生数据" << std::endl;
    std::cout << "\t 0. 退出管理系统" << std::endl;




}
void create_table(MYSQL& mysql){
    char Quest[]= "CREATE TABLE IF NOT EXISTS `Student1`(\
    `Id` int AUTO_INCREMENT,\
    `name` varchar(20),\
    `score` double,\
    PRIMARY KEY (`Id`)\
    )ENGINE=InnoDB DEFAULT CHARSET=utf8;";
    int re=mysql_query(&mysql,Quest);
    if(re==0)
        std::cout<<"table already"<<std::endl;
}

bool connect_mysql(MYSQL& mysql){
    const char db_Username[]="root";
    const char db_Password[]="123456";
    const char db_Host[]="localhost";
    const char db_Name[]="sp";
    unsigned long db_Port=3306;
    mysql_init(&mysql);
    mysql_options(&mysql,MYSQL_SET_CHARSET_NAME,"gbk");
    if(mysql_real_connect(&mysql,db_Host,db_Username,db_Password,db_Name,db_Port,NULL,0)==NULL){
        std::cout<<"connect error!!!"<<std::endl;
        return false;
    }
    std::cout<<"connect success!!!"<<std::endl;
    create_table(mysql);
    return true;
}
int getline(){
    int len=0;
    std::ifstream infile("../src/student2.txt",std::ios::in);
    char c;
//    if (!infile.is_open()) {
//        std::cerr << "Error: Unable to open file. ";
//        std::cerr << "Error code: " << errno << std::endl;
//        return -1; // 或者其他适当的错误码
//    }
    while(infile.get(c)){
//        if(c=='\n')len++;
        len++;
        std::cout<<c;
    }
    infile.close();
    std::cout<<"data_len is "<<len-1<<std::endl;
    return len;
}

void filein(MYSQL& mysql){
    int n=getline();
    std::cout<<"already student data:"<<std::endl;
    mysql_options(&mysql,MYSQL_SET_CHARSET_NAME,"gbk");
    std::ifstream  infile("../src/student2.txt",std::ios::in);
    const int N=300;
    const int N2=100;
    std::string temp[N];
    Student* student=new Student[N2];
    int x=0;
    int tempId;
    int tempScore;
    if(!infile.is_open()){
        std::cout<<"file open errr!!!"<<std::endl;
        exit(0);
    }
    else{
        char line[256]={0};
        int i=0;
        while(!infile.eof()&&i<N){
            for(int j=i;j<i+3;j++){
                infile>>temp[j];
                std::cout<<"\t\t"<<temp[j]<<"\t";
            }
            std::cout<<std::endl;
            tempId=atoi(temp[i].c_str());
            tempScore=atoi(temp[i+2].c_str());
            student[x].setId(tempId);
            student[x].setName(temp[i+1]);
            student[x].setScore(tempScore);
            x++;
            i=i+3;
        }
        infile.close();
    }
    std::cout<<"insert into student1 table"<<std::endl;
    for(int i=1;i<x;i++){
        std::string sql = "insert into Student1 values (" + std::to_string(student[i].getId()) + "," + "'" + student[i].getName() + "'" + "," + std::to_string(student[i].getScore()) + ")";
        std::cout<<sql<<std::endl;
        mysql_query(&mysql,sql.c_str());
    }
    delete[] student;
}

void fileout(MYSQL& mysql){
    MYSQL_RES* res;
    MYSQL_ROW row;
    std::ofstream outfile("../src/student2.txt",std::ios::out);
    mysql_query(&mysql,"select * from student1 order by Id");
    res= mysql_store_result(&mysql);
    std::cout<<"data:"<<std::endl;
    std::cout<<"学号\t"<<"名字\t"<<"得分\n"<<std::endl;
    outfile<<"学号\t"<<"名字\t"<<"得分\n"<<std::endl;
    while(row= mysql_fetch_row(res)){
        std::cout<<"\t"<<row[0]<<"\t\t"<<row[1]<<"\t\t"<<row[2]<<std::endl;
        outfile << row[0] << "\t" << row[1] << "\t" << row[2] << std::endl;
    }
    std::cout << "他们将被保存到../src/student2.txt中" << std::endl;
    outfile.close();
    mysql_free_result(res);
}

void query(MYSQL& mysql) // 查询学生数据
{
    MYSQL_RES* res; // 创建一个结果集
    MYSQL_ROW row; // 二维数组存放记录

    std::cout << "您选择了查询学生信息" << std::endl;
    std::cout << "请输入您要查询的选项" << std::endl;
    std::cout << "\t 1. 查询全部学生" << std::endl;
    std::cout << "\t 2. 按学号查询" << std::endl;
    std::cout << "\t 3. 按照名字进行查询" << std::endl;
    std::cout << "\t 4. 按照分数进行查询" << std::endl;
    std::cout << "\t 5.自定义SQL命令进行查询" << std::endl;
    int choice;
    std::string sql;
    std::cin >> choice;
    switch (choice) {
        case 1:
        {
            std::cout << "全体学生信息如下：" << std::endl;
            sql = "select * from student1 order by Id";
            std::cout << "查询的SQL语句如下：" << std::endl << sql << std::endl; // 检查语句
            mysql_query(&mysql, sql.c_str());
            break;
        }
        case 2:
        {
            std::cout << "请输入要查询的学生学号" << std::endl;
            int Id;
            std::cin >> Id;
            sql = "select * from student1 where Id = " + std::to_string(Id) + " order by Id";
            std::cout << "查询的SQL语句如下：" << std::endl << sql << std::endl; // 检查语句
            mysql_query(&mysql, sql.c_str());
            break;

        }
        case 3:
        {
            std::cout << "请输入要查询的学生姓名" << std::endl;
            std::string name;
            std::cin >> name;
            sql = "select * from student1 where name = '" + name + "' order by Id";
            std::cout << "查询的SQL语句如下：" << std::endl << sql << std::endl; // 检查语句
            mysql_query(&mysql, sql.c_str());
            break;

        }
        case 4:
        {
            std::cout << "请输入要查询的学生分数" << std::endl;
            int score;
            std::cin >> score;
            sql = "select * from student1 where score = " + std::to_string(score) + " order by Id";
            std::cout << "查询的SQL语句如下：" << std::endl << sql << std::endl; // 检查语句
            mysql_query(&mysql, sql.c_str());
            break;

        }
        case 5:
        {
            std::cout << "请输入SQL命令语句" << std::endl;
            std::cin.ignore(1024, '\n');
            getline(std::cin, sql);
            std::cout << "查询的SQL语句如下：" << std::endl<< sql << std::endl; // 检查语句
            mysql_query(&mysql, sql.c_str());
            break;
        }
        default:
            std::cout << "输入有误请重试" << std::endl;
    }


    std::cout << "\t\t查询结果如下" << std::endl;
    res = mysql_store_result(&mysql); // 将查询得到的数据存入结果集
    if (res == NULL)
        std::cout << "所有学生均与你查询的数据不匹配" << std::endl;
    else {
        std::cout << "\t学号\t" << "\t姓名\t" << "\t得分\t" << std::endl;
        while (row = mysql_fetch_row(res))
        {
            std::cout << "\t" << row[0] << "\t\t" << row[1] << "\t\t" << row[2] << std::endl;
        }
    }
    mysql_free_result(res);
}

void modify(MYSQL& mysql) // 修改学生数据
{
    int choice;
    int Id;
    std::string name;
    int score;
    std::string sql1;
    std::string sql2;
    std::string sql;
    MYSQL_RES* res;
    MYSQL_ROW row;
    std::cout << "您选择了修改学生信息" << std::endl;
    std::cout << "请输入您要修改的学生的信息及数据" << std::endl;
    std::cout << "\t 1. 按学号修改" << std::endl;
    std::cout << "\t 2. 按名字修改" << std::endl;
    std::cin >> choice;
    switch (choice)
    {
        case 1:
        {
            std::cout << "请输入要修改的学生学号" << std::endl;
            std::cin >> Id;
            sql = "select * from student1 where Id = " + std::to_string(Id) + " order by Id";
            // sql = "select * from student1 where Id =" + to_string(Id);
            mysql_query(&mysql, sql.c_str());
            res = mysql_store_result(&mysql);
            row = mysql_fetch_row(res);
            if (row == NULL)
            {

                std::cout << "不存在该学号的学生" << std::endl;
                break;
            }
            else

                std::cout << "请输入修改之后的学生姓名" << std::endl;
            std::cin >> name;
            std::cout << "请输入修改之后的学生分数" << std::endl;
            std::cin >> score;
            sql1 = "update Student1 set name= '" + name + "' where Id=" + std::to_string(Id);
            sql2 = "update Student1 set score= " + std::to_string(score) + " where Id=" + std::to_string(Id);
            std::cout << "修改的的SQL语句如下：" << std::endl << sql1 << std::endl << sql2 << std::endl; // 检查语句
            mysql_query(&mysql, sql1.c_str());
            mysql_query(&mysql, sql2.c_str());
            break;
        }
        case 2:
        {
            std::cout << "请输入要修改的学生姓名" << std::endl;
            std::cin >> name;
            sql1 = "select * from Student1 where name ='" + name + "'";
            mysql_query(&mysql, sql1.c_str());
            res = mysql_store_result(&mysql);
            row = mysql_fetch_row(res);
            if (row == NULL)
            {

                std::cout << "不存在该姓名的学生" << std::endl;
                break;
            }
            else
                std::cout << "请输入修改之后的学生学号" << std::endl;
            std::cin >> Id;
            std::cout << "请输入修改之后的学生分数" << std::endl;
            std::cin >> score;
            sql1 = "update Student1 set Id= " + std::to_string(Id) + " where name='" + name + "'";
            sql2 = "update Student1 set score= " + std::to_string(score) + " where name='" + name + "'";
            std::cout << "修改的的SQL语句如下：" << std::endl << sql1 << std::endl << sql2 << std::endl; // 检查语句
            mysql_query(&mysql, sql1.c_str());
            mysql_query(&mysql, sql2.c_str());
            break;
        }
        default:
            std::cout << "输入有误请重试" << std::endl;
    }
    //mysql_free_result(res);
}

void insert(MYSQL& mysql)//添加学生信息
{
    int Id;
    std::string name;
    int score;
    MYSQL_RES* res; // 创建一个结果集
    MYSQL_ROW row; // 二维数组存放记录
    std::string sql1;
    std::string sql2;
    std::cout << "您选择了添加学生信息" << std::endl;
    std::cout << "请输入学生学号" << std::endl;
    std::cin >> Id;

    sql1 = "select * from student1 where Id = " + std::to_string(Id) + " order by Id";
    mysql_query(&mysql, sql1.c_str());
    res = mysql_store_result(&mysql);
    row = mysql_fetch_row(res);
    if (row != NULL)
        std::cout << "已存在该学号的学生，系统不允许学号相同，请重新添加或选择修改该学生信息" << std::endl;
    else {
        std::cout << "请输入学生名字" << std::endl;
        std::cin >> name;
        std::cout << "请输入学生得分" << std::endl;
        std::cin >> score;
        sql2 = "insert into Student1 values (" + std::to_string(Id) + "," + "'" + name + "'" + "," + std::to_string(score) + ")";
        std::cout << "插入的SQL语句如下：" << std::endl << sql2 << std::endl; // 检查语句
        mysql_query(&mysql, sql2.c_str());
        // 使用sql命令对数据库进行数据添加
    }
    mysql_free_result(res);
}
void Delete(MYSQL& mysql) // 删除学生数据
{
    int choice = 1;
    int Id;
    std::string name, sql1, sql2;
    int score;
    MYSQL_RES* res;
    MYSQL_ROW row;
    std::cout << "您选择了删除学生信息" << std::endl;
    //std::cout << "请输入您要删除的学生信息" << std::endl;
    std::cout << "\t 1. 按学号删除" << std::endl;
    std::cout << "\t 2. 按名字删除" << std::endl;
    std::cout << "\t 3. 按照分数删除" << std::endl;


    std::cin >> choice;
    switch (choice) {
        case 1:
        {
            std::cout << "请输入该生学号" << std::endl;
            std::cin >> Id;
            sql1 = "select * from Student1 where Id =" + std::to_string(Id);
            mysql_query(&mysql, sql1.c_str());
            res = mysql_store_result(&mysql);
            row = mysql_fetch_row(res);
            if (row == NULL)
            {

                std::cout << "不存在该学号的学生" << std::endl;
                break;
            }
            else
                sql2 = "delete  from Student1 where Id= " + std::to_string(Id);
            std::cout << "删除的SQL语句如下：" << std::endl << sql2 << std::endl; // 检查语句
            mysql_query(&mysql, sql2.c_str());
            break;
        }
        case 2:
        {
            std::cout << "请输入该生姓名" << std::endl;

            std::cin >> name;
            sql1 = "select * from Student1 where name ='" + name + "'";
            mysql_query(&mysql, sql1.c_str());
            res = mysql_store_result(&mysql);
            row = mysql_fetch_row(res);
            if (row == NULL)
            {

                std::cout << "不存在该姓名的学生" << std::endl;
                break;
            }
            else
                sql2 = "delete  from Student1 where name= '" + name + "'";
            std::cout << "删除的SQL语句如下：" << std::endl << sql2 << std::endl; // 检查语句
            mysql_query(&mysql, sql2.c_str());
            break;
        }
        case 3:
        {
            std::cout << "您确定要使用分数来删除信息吗，该操作可能会影响多名学生" << std::endl;
            std::cout << "1.确定\t 2.取消" << std::endl;
            int c = 0;
            std::cin >> c;
            if (c != 1)
            {
                std::cout << "您选择了取消操作" << std::endl; break;
            }
            else
                std::cout << "您依旧选择了使用分数删除信息！" << std::endl;
            std::cout << "请选择要删除的分数" << std::endl;

            std::cin >> score;
            sql1 = "select * from Student1 where score =" + std::to_string(score);
            mysql_query(&mysql, sql1.c_str());
            res = mysql_store_result(&mysql);
            row = mysql_fetch_row(res);
            if (row == NULL)
            {

                std::cout << "不存在该分数的学生" << std::endl;
                break;
            }
            else
                sql2 = "delete  from Student1 where score= " + std::to_string(score);
            std::cout << "删除的SQL语句如下：" << std::endl << sql2 << std::endl; // 检查语句
            mysql_query(&mysql, sql2.c_str());
            break;
        }
        default:
            std::cout << "您输入的选项有误，请重新输入" << std::endl;
    }
}

Students.cpp

#include "Student.h"
int Student::getId() {
    return Id;
}
std::string Student::getName() {
    return name;
}
int Student::getScore() {
    return score;
}
void  Student::setId(int &id) {
    Id=id;
}
void Student::setName(std::string& Name) {
    name=Name;
}
void Student::setScore(int &Score) {
    score=Score;
}

student2.txt

学号 姓名 成绩
21 张三 98
22 李四 45

CMakeLists.txt

cmake_minimum_required(VERSION 3.20)
project(new_projects)

set(CMAKE_CXX_STANDARD 17)

include_directories(include)

include_directories(D:/develop/MySQL/MySQL\ Server\ 8.0/include)
link_directories(D:/develop/MySQL/MySQL\ Server\ 8.0/lib)
link_libraries(libmysql)

aux_source_directory(src DIR_SRCS)

add_executable(new_projects ${DIR_SRCS})

AUTO_INCREMENT是主键，主键具有唯一性