mysql基礎：mysql與C結合執行個體

一個簡單的mysql與C的互動，使用了一些mysql的C API！

老鳥掠過，新手可以看看！

/******************************************  本檔案學習mysql的database使用  學習mysql的C介面  包括初始化db，檢查資料庫是否存在，不存在就建立。  檢查表是否存在，不存在則建立 *****************************************/#include <stdio.h>#include <stdlib.h>#include <string.h>//需要包含mysql的標頭檔，/usr/include/mysql///編譯的時候需要加上-L/usr/lib/ -lmysqlclient -I/usr/include/mysql選項#include <mysql.h> //基本的標頭檔，一些重要結構體的聲明#include <errmsg.h>//錯誤資訊的存放#include <mysql_version.h>  //包含當前mysql的版本資訊//////////////////全部變數，宏定義//////////////////////#define DEBUG#define SERVER_HOST "localhost"  //mysql的遠程地址#define SERVER_USER "root"      //資料庫登入名稱#define SERVER_PWD  "123"  //資料庫登入密碼#define DB_NAME     "tmp_db"    //建立資料庫的名字#define TABLE_NAME  "mytables"  //庫中的表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會分配記憶體，需要使用mysql_free_result釋放        mysql_free_result(res);    }    if(!row)  //沒有這個資料庫，則建立    {        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;}

編譯的方法：最後的-I一定要注意檢查這個目錄是不是存在，否則會報錯

gcc -o mysql mysql.c -L/usr/lib/ -lmysqlclient -I/usr/include/mysql

報錯：

root@jack-desktop:~# gcc -o mysql mysql.c -L/usr/lib/ -lmysqlclientgcc: mysql.c: 沒有那個檔案或目錄root@jack-desktop:~# root@jack-desktop:~# root@jack-desktop:~# cd myc/root@jack-desktop:myc# gcc -o mysql mysql.c -L/usr/lib/ -lmysqlclientmysql.c:15:73: error: mysql.h: 沒有那個檔案或目錄mysql.c:16:43: error: errmsg.h: 沒有那個檔案或目錄mysql.c:17:63: error: mysql_version.h: 沒有那個檔案或目錄mysql.c:27: error: expected ‘)’ before ‘*’ tokenmysql.c:28: error: expected ‘)’ before ‘*’ tokenmysql.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 oncemysql.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 ‘*’ tokenmysql.c:109: error: expected ‘)’ before ‘*’ token