一个简单的mysql与C的交互，使用了一些mysql的C API！
老鸟掠过，新手能够看看！
/******************************************
本文件学习mysql的database使用
学习mysql的C接口
包括初始化db，检查数据库是否存在，不存在就创建。
检查表是否存在，不存在则创建
*****************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h> //须要包括mysql的头文件，/usr/include/mysql/
//编译的时候须要加上-L/usr/lib/ -lmysqlclient -I/usr/include/mysql选项 #include <mysql.h> //主要的头文件，一些重要结构体的声明
#include <errmsg.h>//错误信息的存放
#include <mysql_version.h> //包括当前mysql的版本号信息
//////////////////所有变量，宏定义//////////////////////
#define DEBUG
#define SERVER_HOST "localhost" //mysql的远程地址
#define SERVER_USER "root" //数据库登录名
#define SERVER_PWD "123" //数据库登录password #define DB_NAME "tmp_db" //新建数据库的名字
#define TABLE_NAME "mytables" //库中的表 int check_tbl(MYSQL* mysql,char *name);
int check_db(MYSQL *mysql,char *db_name); int init_db()
{ int err=0;
MYSQL mysql; if(!mysql_init(&mysql)){
perror("mysql_init:");
exit(1);
} if(!mysql_real_connect(&mysql,SERVER_HOST,SERVER_USER,SERVER_PWD,NULL,0,NULL,0))
{
perror("mysql_real_connect");
exit(1);
}
printf("connected.....\n"); err = check_db(&mysql,DB_NAME);
if(err != 0)
{
printf("create db is err!\n");
mysql_close(&mysql);
exit(1);
}
//select which db
if(mysql_select_db(&mysql,DB_NAME)) //return 0 is success ,!0 is err
{
perror("mysql_select_db:");
mysql_close(&mysql);
exit(1);
}
//chuangjianbiao
if((err=check_tbl(&mysql,TABLE_NAME))!=0)
{
printf("check_tbl is err!\n");
mysql_close(&mysql);
exit(1);
}
mysql_close(&mysql);
return 0;
} int check_db(MYSQL *mysql,char *db_name)
{
MYSQL_ROW row = NULL;
MYSQL_RES *res = NULL; res = mysql_list_dbs(mysql,NULL);
if(res)
{
while((row = mysql_fetch_row(res))!=NULL)
{
printf("db is %s\n",row[0]);
if(strcmp(row[0],db_name)==0)
{
printf("find db %s\n",db_name);
break;
}
}
//mysql_list_dbs会分配内存，须要使用mysql_free_result释放
mysql_free_result(res);
}
if(!row) //没有这个数据库，则建立
{
char buf[128]={0};
strcpy(buf,"CREATE DATABASE ");
strcat(buf,db_name);
#ifdef DEBUG
printf("%s\n",buf);
#endif
if(mysql_query(mysql,buf)){
fprintf(stderr,"Query failed (%s)\n",mysql_error(mysql));
exit(1);
}
}
return 0;
} int check_tbl(MYSQL* mysql,char *name)
{
if(name == NULL)
return 0;
MYSQL_ROW row=NULL;
MYSQL_RES *res = NULL;
res = mysql_list_tables(mysql,NULL);
if(res)
{
while((row = mysql_fetch_row(res))!=NULL)
{
printf("tables is %s\n",row[0]);
if(strcmp(row[0],name) == 0)
{
printf("find the table !\n");
break;
}
}
mysql_free_result(res);
}
if(!row) //create table
{
char buf[128]={0};
char qbuf[128]={0};
snprintf(buf,sizeof(buf),"%s (name VARCHAR(20),sex char(1),score int(3));",TABLE_NAME);
strcpy(qbuf,"CREATE TABLE ");
strcat(qbuf,buf);
//#ifdef DEBUG
printf("%s\n",qbuf);
//#endif
if(mysql_query(mysql,qbuf)){
fprintf(stderr,"Query failed (%s)\n",mysql_error(mysql));
exit(1);
}
}
return 0;
} int main()
{
int err=0;
err = init_db(); return 0;
}
编译的方法：最后的-I一定要注意检查这个文件夹是不是存在，否则会报错
gcc -o mysql mysql.c -L/usr/lib/ -lmysqlclient -I/usr/include/mysql
报错：
root@jack-desktop:~# gcc -o mysql mysql.c -L/usr/lib/ -lmysqlclient
gcc: mysql.c: 没有那个文件或文件夹
root@jack-desktop:~#
root@jack-desktop:~#
root@jack-desktop:~# cd myc/
root@jack-desktop:myc# gcc -o mysql mysql.c -L/usr/lib/ -lmysqlclient
mysql.c:15:73: error: mysql.h: 没有那个文件或文件夹
mysql.c:16:43: error: errmsg.h: 没有那个文件或文件夹
mysql.c:17:63: error: mysql_version.h: 没有那个文件或文件夹
mysql.c:27: error: expected ‘)’ before ‘*’ token
mysql.c:28: error: expected ‘)’ before ‘*’ token
mysql.c: In function ‘init_db’:
mysql.c:34: error: ‘MYSQL’ undeclared (first use in this function)
mysql.c:34: error: (Each undeclared identifier is reported only once
mysql.c:34: error: for each function it appears in.)
mysql.c:34: error: expected ‘;’ before ‘mysql’
mysql.c:36: error: ‘mysql’ undeclared (first use in this function)
mysql.c: At top level:
mysql.c:73: error: expected ‘)’ before ‘*’ token
mysql.c:109: error: expected ‘)’ before ‘*’ token