用c语言连接mysql

• 安装mysql,请自行百度
• 安装mysql.h函数库

sudo apt-get install libmysqlclient-dev

执行之后就可以看到/usr/include/mysql目录了
然后开始我们的链接.
首先看我的数据库

mysql> show databases; +--------------------+
| Database | +--------------------+
| information_schema | | chat_room          |
| mysql              |
| mysql_shiyan | | performance_schema |
| sys | +--------------------+
6 rows in set (0.00 sec)
mysql> use chat_room; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed
mysql> show tables; +---------------------+
| Tables_in_chat_room | +---------------------+
| user_message | +---------------------+
1 row in set (0.00 sec)
mysql> select * from user_message; +------+-------+--------+
| ID | name | passwd | +------+-------+--------+
|    1 | linux | linux  |
| 2 | lyt | lyt | +------+-------+--------+
2 rows in set (0.00 sec)

可以看到,我在chat_room数据库中有user_message这张表,我们现在要做的就是读出这张表里的数据.
直接上代码

#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<mysql/mysql.h>

int main(void)
{
    char *sql;
    sql="SELECT * FROM user_message;";
    int res;//执行sql语句后的返回标志
    MYSQL_RES *res_ptr;//指向查询结果的指针
    MYSQL_FIELD *field;//字段结构指针
    MYSQL_ROW result_row;//按行返回查询信息
    int row,column;//查询返回的行数和列数
    MYSQL *conn;//一个数据库链接指针
    int i,j;

    //初始化连接句柄
    conn = mysql_init(NULL);

    if(conn == NULL) { //如果返回NULL说明初始化失败
        printf("mysql_init failed!\n");
        return EXIT_FAILURE;
    }

    //进行实际连接
    //参数　conn连接句柄，host　mysql所在的主机或地址,user用户名,passwd密码,database_name数据库名,后面的都是默认
    conn = mysql_real_connect(conn,"localhost","lyt","","chat_room",0,NULL,0);
    if (conn) {
        printf("Connection success!\n");
    } else {
        printf("Connection failed!\n");
    }
    mysql_query(conn,"set names gbk");//防止乱码。设置和数据库的编码一致就不会乱码

    res = mysql_query(conn,sql);//正确返回0
    if(res) {
        perror("my_query");
        mysql_close(conn);
        exit(0);
    } else{
        //把查询结果给res_ptr
        res_ptr = mysql_store_result(conn);
        //如果结果不为空,则输出
        if(res_ptr) {
            column = mysql_num_fields(res_ptr);
            row = mysql_num_rows(res_ptr);
            printf("查到%d行\n",row);
            //输出结果的字段名
            for(i = 0;field = mysql_fetch_field(res_ptr);i++) {
                printf("%10s",field->name);
            }
            puts("");
            //按行输出结果
            for(i = 1;i < row+1;i++){
                result_row = mysql_fetch_row(res_ptr);
                for(j = 0;j< column;j++) {
                    printf("%10s",result_row[j]);
                }
                puts("");
            }
        }
    }
    //退出前关闭连接
    mysql_close(conn);

    return 0;
}

结果

gcc -o mysql a.c -L/usr/lib/mysql -lmysqlclient
./mysql 
Connection success!
查到2行
        ID      name    passwd
         1     linux     linux
         2       lyt       lyt

注释写的相当清楚,有什么不清楚的可以给我留言,大家一块学习!