基于数据库MySQL的简易学生信息管理系统

     2.编写代码

#include <stdlib.h>
#include <stdio.h>
#include <mysql.h>
#include <ctype.h>
#include <curses.h>


//#define MAX_PASSWD_LEN 16


void printf_mune(void);
char *getPasswd(void);
int insert_student(void);
int delete_student(void);
int inquiry_student(void);





int main(int argc,char** argv)
{
    char user[20];
    char passwd[20];
    char c;
    int i;
    printf("***********************************************************\n");
    printf("*      welcome to student information managent system     *\n");
    printf("***********************************************************\n");
//    printf("             user: ______________\b\b\b\b\b\b\b\b\n");
//    printf("            psaawd:______\b\b\b\b\b\b\n");

    while(1){
        
        printf("                    user:");
        scanf("%s", user);

         printf("                   passwd:");
    
         scanf("%s",passwd);
       
      /*  while ((c=getch())!=‘\n‘)
        {
            if (i<MAX_PASSWD_LEN && isprint(c))   //isprint函数判断c是否是可打印字符
            {
                passwd[i++] = c;
                putchar(‘*‘);
            }
            else if (i>0 && c==‘\b‘)
            {
                --i;
                putchar(‘\b‘);
                putchar(‘ ‘);
                putchar(‘\b‘);
            }
        }
        putchar(‘\n‘);
        passwd[i] = ‘\0‘; */

        if(!strncmp(user, "qigaohua", 8)){
            if(!strncmp(passwd, "123456", 6))
                break;
            else {
                printf("passwd error\n");
                continue;
            }
        }else{
            printf("user error\n");
            continue;
        }
    }

    printf("login sucess\n");
    while(1){
         printf_mune();
         getchar();                   //问题1  必须加
         c = fgetc(stdin);
         switch(c){
            case ‘I‘:
                insert_student();
                break;
            case ‘D‘:
                delete_student();
                break;
            case ‘S‘:
                inquiry_student();
                break;
            case ‘Q‘:
                return 0;
                break;
            default:
                ;    
         }
    }
    printf("exit sucess\n");
    return 0;
    
}

/*getc()和getchar()函数想必大家都经常用到，但它们都在输入的同时显示输入内容，并由回车终止输入。
为了不显示输入内容，我们调用另外一个函数getch()，它包含在头文件中。该函数可以在输入的同时不显示
输入内容，并在输入完成后不需回车而自动终止输入。与此同时，该头文件中还包含另外一个函数getche()，
它和getch()功能相同，唯一的区别是输入的同时显示输入的内容。本文我们只用到getch();*/
/*char *getPasswd()
{
    unsigned char c;
    passwd =(char*)malloc(8);
    int i = 0;

    while ((c=getch())!=‘\r‘)
    {
        if (i<MAX_PASSWD_LEN && isprint(c))   //isprint函数判断c是否是可打印字符
        {
            passwd[i++] = c;
            putchar(‘*‘);
        }
        else if (i>0 && c==‘\b‘)
        {
            --i;
            putchar(‘\b‘);
            putchar(‘ ‘);
            putchar(‘\b‘);
        }
    }
    putchar(‘\n‘);
    passwd[i] = ‘\0‘;
    
    return passwd;
}*/


void printf_mune(void)
{
    printf("The following operations can be performed\n");
    printf("1. insert student information             input I\n");
    printf("2. delete student information                    input D\n");
    printf("3. inquiry student information                   input S\n");
    printf("4. exit student information managent system      input Q\n");
}

int insert_student(void)
{
    MYSQL mysql;
    char sql[100];
    char k;
    char id[10], name[20], sex[5],birth[15],potility[20];

    mysql_init(&mysql);
    if(!mysql_real_connect(&mysql, "localhost", "root",NULL,"school_db",0,NULL,0)){
        printf("ERROR: %d--%s\n", mysql_errno(&mysql), mysql_error(&mysql));
        exit(-1);
    }
    mysql_set_character_set(&mysql, "utf8");
    while(1) {
        
        printf("please input student information\n");
        printf("student_id: ");
        fflush(stdin);
        scanf("%s",id);
//        fgets(id, 10, stdin);
        printf("\nname: ");
        scanf("%s",name);
//        fgets(name, 20, stdin);

        printf("\nsex: ");
        scanf("%s",sex);

        printf("\nbirth: ");
        scanf("%s",birth);
//        fgets(birth, 15, stdin);

        printf("\npolitily: ");
        scanf("%s",potility);
//        fgets(potility, 20, stdin);

        printf("\nplease input y or n or q\n");
//        read(stdin, k, 1);
           getchar();                       //注意要加
        k = fgetc(stdin);
        if(k == ‘n‘)
            continue;
        else if(k == ‘q‘)
            break;
        else if(k == ‘y‘){
            sprintf(sql, "insert into students values (\"%s\", \"%s\", \"%s\", \"%s\", \"%s\");", id, name,sex, birth, potility);
            printf("\n%s",sql);

            if(mysql_query(&mysql, sql)){
                printf("\ninsert failed: %d--%s\n", mysql_errno(&mysql), mysql_error(&mysql));
                continue;
            }
            printf("\ninsert sucess\n");

            printf("you want exit? input q\n");
            getchar();
            k = fgetc(stdin);
            if(k == ‘q‘)
                break;
        }    
    }
    mysql_close(&mysql);
    return 0;
}

int delete_student(void)
{
    MYSQL mysql;
    char sql[100];
    char id[10], name[20];
    char k;

    mysql_init(&mysql);
    if(!mysql_real_connect(&mysql, "localhost", "root",NULL,"school_db",0,NULL,0)){
        printf("ERROR: %d--%s\n", mysql_errno(&mysql), mysql_error(&mysql));
        exit(-1);
    }    
    mysql_set_character_set(&mysql, "utf8");

    while(1){
        printf("please input you want delete student id or name, selset i or n or q\n");
        getchar();              //注意
        k = fgetc(stdin);
        if(k == ‘i‘) {
            printf("student id: ");
            scanf("%s",id);
            //fgets(id, 10, stdin);
            sprintf(sql, "delete from students where student_id=\"%s\";", id);
        }else if(k == ‘n‘){
            printf("\nstudent name: ");
            scanf("%s",name);
            //fgets(name, 20, stdin);
            sprintf(sql, "delete from students where name=\"%s\";", name);            
        }else if(k == ‘q‘)
            break;
        printf("\nyou are sure? y or n or q\n");
        getchar();
        k = fgetc(stdin);
        if(k == ‘n‘)
            continue;
        else if(k == ‘y‘){
            if(mysql_query(&mysql, sql)){
                printf("delete failed: %d--%s\n", mysql_errno(&mysql), mysql_error(&mysql));
                continue;
            }
            printf("delete sucess\n");    
        }
        else if(k == ‘q‘)
            break;
    }
    mysql_close(&mysql);
    return 0;
}

int inquiry_student(void)
{
    MYSQL mysql;
    MYSQL_RES *res;
    MYSQL_ROW  row;
    MYSQL_FIELD *filed;

    char sql[100];
    char id[10], name[20];
    char k;
    
    int column,i;

    my_ulonglong backrows;

    mysql_init(&mysql);
    if(!mysql_real_connect(&mysql, "localhost", "root",NULL,"school_db",0,NULL,0)){
        printf("ERROR: %d--%s\n", mysql_errno(&mysql), mysql_error(&mysql));
        exit(-1);
    }    
    mysql_set_character_set(&mysql, "utf8");
    
    while(1){
        printf("please input you want inquiry student id or name, selset i or n or q\n");
        getchar();   //标记
        k = fgetc(stdin);
        if(k == ‘i‘) {
            printf("student id: ");
            scanf("%s", id);
            //fgets(id, 10, stdin);
            sprintf(sql, "select * from students where student_id=\"%s\";", id);
            printf("sql request:%s\n", sql);
        }else if(k == ‘n‘) {
            printf("\nstudent name: ");
            scanf("%s", name);
            //fgets(name, 20, stdin);
            sprintf(sql, "select * from students where name=\"%s\";", name);
            printf("sql request:%s\n", sql);
        }else if(k == ‘q‘)
            break;
        printf("\nyou are sure? y or n or q\n");
        getchar();
        k = fgetc(stdin);
        if(k == ‘n‘)
            continue;
        else if(k == ‘y‘){
            if(mysql_query(&mysql, sql)){
                printf("delete failed: %d--%s\n", mysql_errno(&mysql), mysql_error(&mysql));
                continue;
            }
            
            res = mysql_store_result(&mysql);   //首先判断res是否为NULL来判断是否有数据，但是失败了，不知道为什么，最后用了下面函数
            backrows = mysql_num_rows(res);//返回上面函数返回结果的行数
            
            if(backrows != 0){                
                column = mysql_num_fields(res);

                while((row = mysql_fetch_row(res))){
                    i = 0;
                    while((filed = mysql_fetch_field(res)) != NULL && (i < column)){
                        printf("%s:", filed->name);
                        printf("%s", row[i++]);
                        printf("\n");
                    }
                    printf("\n");
                }

            }else{
                printf("no data found\n");
                continue;
            }
            
            printf("inquiry sucess\n");    
        }
        else if(k == ‘q‘)
            break;
    }
    mysql_close(&mysql);
    return 0;
}

　  3.编译

　　　gcc -o students students.c -I /usr/include/mysql/ -L /usr/lib/mysql/ -lmysqlclient -lcurses

三：运行现象

    最后选择Q退出整个系统

虽然所要求的功能基本实现，但是比预先心里所想的还有许多差距，看看程序就知道，改了有改，确实没时间了，就这样吧。

基于数据库MySQL的简易学生信息管理系统

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