c与mysql连接和一个简单查询的例子

    连接数据库test 用户名root密码abc
    在里面有一个username的表，describe username结果如下
    mysql> describe username;
    +----------+-------------+------+-----+---------+-------+
    | Field    | Type        | Null | Key | Default | Extra |
    +----------+-------------+------+-----+---------+-------+
    | id       | int(10)     | YES  |     | NULL    |       |
    | username | varchar(32) |      | PRI |         |       |
    +----------+-------------+------+-----+---------+-------+

    mysql> select * from username;
    +------+----------+
    | id   | username |
    +------+----------+
    |    1 | sfs      |
    +------+----------+
    1 row in set (0.00 sec)

    [b:f09d522785]本文目的查找执行select id from username这个语句并打印结果[/b:f09d522785]
    [code:1:f09d522785]
    #include <unistd.h>
    #include <arpa/inet.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <mysql/mysql.h>
    #include <signal.h>
    #include <errno.h>
    #include <syslog.h>
    MYSQL mysql;
    main()
    {
    char host[32]="localhost";
    char user[32]="root";
    char passwd[32]="abc";
    char dbname[32]="test";

    if( mysql_init(&mysql) == NULL )
    {
    syslog(LOG_USER|LOG_INFO,"inital mysql handle error\n");
    return 1;
    }
    if (mysql_real_connect(&mysql,host,user,passwd,dbname,0,NULL,0) == NULL)
    {
    syslog(LOG_USER|LOG_INFO, "Failed to connect to database: Error: %s\n",mysql_error(&mysql));
    return 1;
    }
    else syslog(LOG_USER|LOG_INFO, "connect to database: \n");
    find_ps();
    db_close();
    return 0;
    }
    int db_close()
    {
            mysql_close(&mysql);
             return 0;
    }

    int  find_ps ()
    {
    MYSQL_ROW m_row;
    MYSQL_RES *m_res;
    char sql[1024],username[32];
    int res=1;
    int *id;
    sprintf(sql,"select id from username");
    if(mysql_query(&mysql,sql) != 0)
    {
    syslog(LOG_USER|LOG_INFO, "select ps_info Error: %s\n",mysql_error(&mysql));
    return res;
    }
    m_res = mysql_store_result(&mysql);
    if(m_res==NULL)
    {
    syslog(LOG_USER|LOG_INFO, "select username Error: %s\n",mysql_error(&mysql));
    res = 3;
    return res;
    }
    if(m_row = mysql_fetch_row(m_res))
    {
    printf("m_row=%d\n",atoi(m_row[0]));
    res = 0;
    }
    mysql_free_result(m_res);
    return res;
    }
    [/code:1:f09d522785]