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..... "); err = check_db(&mysql,DB_NAME); if(err != 0) { printf("create db is err! "); 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! "); 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 ",row[0]); if(strcmp(row[0],db_name)==0) { printf("find db %s ",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 ",buf); #endif if(mysql_query(mysql,buf)){ fprintf(stderr,"Query failed (%s) ",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 ",row[0]); if(strcmp(row[0],name) == 0) { printf("find the table ! "); 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 ",qbuf); //#endif if(mysql_query(mysql,qbuf)){ fprintf(stderr,"Query failed (%s) ",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