最近写了哟个程序需要用C语言连接MySQL，是基于Ubuntu的，我就写了如下的代码（其中包括了UDP协议部分）
事实上我们就是通过系统自带的头文件通过SQL语句对数据库进行操作，这应该对熟悉数据库语言的人就非常简单了
附上可用的代码：
#include/* These are the usual header files */#include #include /* for close() */#include #include #include #include #include #include #define PORT 50001 /* Port that will be opened */#define MAXDATASIZE 100 /* Max number of bytes of data */MYSQL *mysql_conn;char *head="head";char *drift="drift";const char *host_name="localhost";const char *user_name="user";const char *password="password";const char *db_name="dbname";const unsigned int db_port=3306;char sql[512];void getMessageInsert(char receive_msg[]){int i=0,res=0;char temp[100];char *p[12];char *buff;strcpy(temp,receive_msg);buff=temp;for(i=0;i<12;i++)p[i]=NULL;//printf("%s\n",buff);char *token=strtok(buff,",");p[0]=token;i=0;while(token!=NULL){//printf("%s,i=%d\t",p[i],i);token=strtok(NULL,",");p[++i]=token;if(i>=11)break;}//printf("i=%d\n",i);if(i>=11&&strcmp(p[0],head)==0&&strcmp(p[11],drift)==0){// printf("%d,%d",strcmp(p[0],head),i); //printf("saved\n"); sprintf(sql,"insert into he%s(data_1,data_2,data_3,data_4,data_5,data_6,data_7,judge,longitude,latitude)values(%s,%s,%s,%s,%s,%s,%s,0,%s,%s)",p[1],p[2],p[3],p[4],p[5],p[6],p[7],p[8],p[9],p[10]); sprintf(sql,"insert into he%s(data_1,data_2,data_3,data_4,data_5,data_6,data_7,judge,longitude,latitude)values(%s,%s,%s,%s,%s,%s,%s,0,%s,%s)",p[1],p[2],p[3],p[4],p[5],p[6],p[7],p[8],p[9],p[10]); res=mysql_query(mysql_conn,sql); printf("%s\n",sql);if (!res) { //输出受影响的行数 printf("Inserted %lu rows\n",(unsigned long)mysql_affected_rows(mysql_conn)); } else { //打印出错误代码及详细信息 fprintf(stderr, "Insert error %d: %sn",mysql_errno(mysql_conn),mysql_error(mysql_conn)); sprintf(sql,"create table he%s(number int(9) unsigned not null auto_increment,p_data timestamp not null default current_timestamp,data_1 int(4) unsigned not null,data_2 int(4) not null,data_3 int(4) not null,data_4 int(4) not null,data_5 int(4) not null,data_6 int(4) not null,data_7 int(4) not null,judge tinyint(1) default 0,longitude decimal(11,8) not null,latitude decimal(11,8) not null,primary key(number))",p[1]); res=mysql_query(mysql_conn, sql); }}main(){int sockfd; /* socket descriptors */struct sockaddr_in server; /* server's address information */struct sockaddr_in client; /* client's address information */socklen_t sin_size;int num;char recvmsg[MAXDATASIZE]; /* buffer for message */char sendmsg[MAXDATASIZE];char condition[] = "quit";//打开数据库mysql_conn=mysql_init(NULL);if(!mysql_real_connect(mysql_conn, host_name, user_name, password, db_name, db_port, NULL, 0)){ printf("connect error"); exit(1);}/* Creating UDP socket */if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {/* handle exception */perror("Creating socket failed.");exit(1);}
代码完成之后就开始编译了，不过问题出现了
root@iZ28j1w4g5uZ:/home/myCProgrammer# vim udp_save.c root@iZ28j1w4g5uZ:/home/myCProgrammer# gcc udp_save.c -o udp_save /tmp/ccaY48dW.o: In function getMessageInsert': udp_save.c:(.text+0x201): undefined reference tomysql_query’ udp_save.c:(.text+0x229): undefined reference to mysql_affected_rows' udp_save.c:(.text+0x248): undefined reference tomysql_error’ udp_save.c:(.text+0x257): undefined reference to mysql_errno' udp_save.c:(.text+0x2a8): undefined reference tomysql_query’ /tmp/ccaY48dW.o: In function main': udp_save.c:(.text+0x301): undefined reference tomysql_init’ udp_save.c:(.text+0x354): undefined reference to `mysql_real_connect’ collect2: error: ld returned 1 exit status root@iZ28j1w4g5uZ:/home/myCProgrammer#
当然，我们换一种编译方式：
gcc -o udp_save $(mysql_config --cflags) udp_save.c $(mysql_config --libs) 这样就可以通过编译了