C基础 mariadb处理的简单实例_C语言教程-查字典教程网

摘要：引言MariaDB是一款灰常不错开源数据库.这里直接用它来解决业务问题.业务需求：现在数据库中表示按照天分表的.突然我们需要按照月来处理数据...

引言

MariaDB 是一款灰常不错开源数据库. 这里直接用它来解决业务问题.

业务需求：

现在数据库中表示按照天分表的. 突然我们需要按照月来处理数据.

例如输入一个玩家id, 查找这个玩家这个月内看了一件事几次. 我们先搭建一个环境.

操作系统：

Linux version 4.4.0-22-generic (buildd@lgw01-41) (gcc version 5.3.1 20160413 (Ubuntu 5.3.1-14ubuntu2) ) #40-Ubuntu SMP Thu May 12 22:03:46 UTC 2016

首先安装 MariaDB数据库

sudo apt-get install mariadb-server sudo apt-get install mariadb-client sudo apt-get install libmariadb2 sudo apt-get install libmariadb-client-lgpl-dev sudo apt-get install libreoffice-mysql-connector

后面是C访问 MariaDB驱动. 这里扯一点, 目前关于MariaDB不懂问题, 搜不见直接当成mysql开始搜.

MariaDB安装成功后默认是开启的, 看下面图描述

C基础 mariadb处理的简单实例1

后面搭建测试环境首先看 oss_musicelves.sql

-- MySQL dump 10.10 -- -- Host: localhost Database: oss_log -- ------------------------------------------------------ -- Server version 5.5.24-tmysql-1.4 /*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */; /*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */; /*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */; /*!40101 SET NAMES utf8 */; /*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */; /*!40103 SET TIME_ZONE='+00:00' */; /*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */; /*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */; /*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */; /*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */; -- -- Table structure for table `oss_musicelves` -- DROP TABLE IF EXISTS `oss_musicelves`; CREATE TABLE `oss_musicelves` ( `record_id` bigint(20) NOT NULL AUTO_INCREMENT, `account_id` bigint(20) NOT NULL, `server_id` int(11) NOT NULL, `char_id` bigint(20) NOT NULL, `char_sex` int(11) NOT NULL, `type_id` int(11) NOT NULL, `timeStamp` datetime NOT NULL DEFAULT '0000-00-00 00:00:00', `ptype` int(11) NOT NULL, `specifytype` int(11) NOT NULL, `childtype` int(11) NOT NULL, PRIMARY KEY (`record_id`), KEY `idx_specifytype` (`specifytype`) ) ENGINE=InnoDB AUTO_INCREMENT=32 DEFAULT CHARSET=latin1; -- -- Dumping data for table `oss_musicelves` -- /*!40000 ALTER TABLE `oss_musicelves` DISABLE KEYS */; LOCK TABLES `oss_musicelves` WRITE; INSERT INTO `oss_musicelves` VALUES (1,411948833,84869352,27899597414400801,0,1812,'2016-05-31 14:27:41',0,1,1),(2,1344702709,90964200,30422720614402293,0,1812,'2016-05-31 14:58:26',0,1,1),(3,706409913,90964200,30422720614401465,1,1812,'2016-05-31 14:58:27',0,1,2),(4,706409913,392964857,30422720614401465,1,1812,'2016-05-31 14:58:59',0,2,4),(5,1344702709,392964857,30422720614402293,0,1812,'2016-05-31 14:58:59',0,2,4),(6,706409913,90964200,30422720614401465,1,1812,'2016-05-31 15:04:52',0,1,2),(7,706409913,392964857,30422720614401465,1,1812,'2016-05-31 15:05:54',0,2,4),(8,1344702709,392964857,30422720614402293,0,1812,'2016-05-31 15:05:54',0,2,4),(9,1344702709,90964200,30422720614402293,0,1812,'2016-05-31 15:10:29',0,1,1),(10,706409913,90964200,30422720614401465,1,1812,'2016-05-31 15:10:32',0,1,2),(11,1344702709,392964857,30422720614402293,0,1812,'2016-05-31 15:10:54',0,2,4),(12,3145910262,90964200,29520779366416374,1,1812,'2016-05-31 15:30:00',0,1,1),(13,1372825842,90964200,30173879500803314,1,1812,'2016-05-31 15:30:01',0,1,2),(14,3145910262,392964857,29520779366416374,1,1812,'2016-05-31 15:30:04',0,2,4),(15,1372825842,392964857,30173879500803314,1,1812,'2016-05-31 15:30:04',0,2,4),(16,3145910262,392964857,29520779366416374,1,1812,'2016-05-31 15:34:24',0,2,4),(17,1372825842,392964857,30173879500803314,1,1812,'2016-05-31 15:34:24',0,2,4),(18,706409913,90964200,30422720614401465,1,1812,'2016-05-31 15:40:14',0,1,1),(19,1344702709,90964200,30422720614402293,0,1812,'2016-05-31 15:40:16',0,1,2),(20,3145910262,392964857,29520779366416374,1,1812,'2016-05-31 15:42:19',0,2,4),(21,1372825842,392964857,30173879500803314,1,1812,'2016-05-31 15:42:19',0,2,4),(22,1027763684,90964200,30175730790400484,0,1812,'2016-05-31 16:56:33',1,1,1),(23,1372825842,90964200,30173879500803314,1,1812,'2016-05-31 16:56:50',0,1,2),(24,1372825842,392964857,30173879500803314,1,1812,'2016-05-31 16:57:37',0,2,3),(25,1027763684,392964857,30175730790400484,0,1812,'2016-05-31 16:57:37',1,2,3),(26,1372825842,392964857,30173879500803314,1,1812,'2016-05-31 17:04:33',0,2,3),(27,1027763684,392964857,30175730790400484,0,1812,'2016-05-31 17:04:33',1,2,3),(28,1027763684,90964200,30175730790400484,0,1812,'2016-05-31 17:14:15',1,1,2),(29,1372825842,392964857,30173879500803314,1,1812,'2016-05-31 17:14:50',0,2,3),(30,1027763684,392964857,30175730790400484,0,1812,'2016-05-31 17:14:50',1,2,3),(31,751699770,90964200,30175199027201850,1,1812,'2016-05-31 18:14:59',1,1,1); UNLOCK TABLES; /*!40000 ALTER TABLE `oss_musicelves` ENABLE KEYS */; /*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */; /*!40101 SET SQL_MODE=@OLD_SQL_MODE */; /*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */; /*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */; /*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */; /*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */; /*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */; /*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

这个 oss_musicelves.sql 文件主要功能是创建oss_musicelves数据库, 并填充数据.

还有一个搭建环境的脚本 mariadb_test.sql 和上一个sql文件放在同一个目录下

# 创建一个测试数据库 create database oss_log; # 进入oss_log 数据库 use oss_log; # 创建 oss_musicelves 数据库, 并导入数据 source oss_musicelves.sql; # 批量创建表和数据 create table 2016_6_1_oss_musicelves select * from oss_musicelves; create table 2016_6_2_oss_musicelves select * from oss_musicelves; create table 2016_6_3_oss_musicelves select * from oss_musicelves; create table 2016_6_4_oss_musicelves select * from oss_musicelves; create table 2016_6_5_oss_musicelves select * from oss_musicelves; create table 2016_6_9_oss_musicelves select * from oss_musicelves; create table 2016_6_10_oss_musicelves select * from oss_musicelves; create table 2016_6_12_oss_musicelves select * from oss_musicelves; # 查询表是否创建成功 show tables; # 这里处理拿到的数据 select distinct table_name from information_schema.columns where table_name like '2016_6_%_oss_musicelves';

直接放在 MariaDB控制台中直接刷进去. 搭建的具体环境如下

C基础 mariadb处理的简单实例2

到这里环境基本搭建好了. MariaDB入门等等, 完全可以当做mysql 学习温故一遍.

前言

上面问题就是原本是 select * from oss_musicelves; 就可以解决的问题.

这里需要输入年和月外加一些特殊条件 . select * from %_%_%_oss_musicelves; 解决. 单纯用sql脚本也可以解决.非常复杂.用的不熟.

这里首先通过 shell 脚本处理

touch getmouths.sh chmod +x getmouths.sh vi getmouths.sh

具体的脚本内容如下

#!/bin/sh #得到输入的玩家ptid if [ $# -lt 1 ] then echo "uage: $0 [ptid]" exit -1 fi ptid=$1 mouth=$(date +%m | sed s'/^0//') #第一个参数是月份 if [ $# -ge 2 ] then mouth=$2 fi #第二个参数是年 year=$(date +%Y) if [ $# -ge 3 ] then year=$3 fi #得到查询的随机表名 tbname=""${year}_${mouth}_%_oss_musicelves"" #这里得到mysql 中所有合法表名 rm -rf __tmp touch __tmp #开始查询数据库了, 需要以root权限启动这个脚本 mysql -e "select distinct table_name from information_schema.columns where table_name like $tbname" | awk 'NR>1' | while read name do mysql -e "select count(*) from oss_log.$name where specifytype = 1 and char_id = $ptid" | awk 'NR>1' | while read cut do echo "$name : $cut" echo $cut >> __tmp break done done #统计表里面的数据 sum=$(cat __tmp | awk '{s+=$1} END {print s}') rm -rf __tmp # 最后输出统计结果 echo "$year-$mouth sum: $sum"

使用脚本截图

C基础 mariadb处理的简单实例3

通过shell可以完成我们的需求. Linux上shell真好用. window的bat不好用.

正文

第一部分 : 让C调用MariaDB跑通

先看测试Demo mariadb_demo.c

#include <stdio.h> #include <stdlib.h> #include <mysql.h> /* * 第一个 mariadb程序 */ int main(int argc, char *argv[]) { // 创建数据连接对象 MYSQL *con = mysql_init(NULL); if (con == NULL) { fprintf(stderr, "%sn", mysql_error(con)); exit(EXIT_FAILURE); } if (!mysql_real_connect(con, "localhost", "root", "", NULL, 0, NULL, 0)) { fprintf(stderr, "%sn", mysql_error(con)); mysql_close(con); exit(EXIT_FAILURE); } if (mysql_query(con, "show databases;")) { fprintf(stderr, "%sn", mysql_error(con)); mysql_close(con); exit(EXIT_FAILURE); } puts("mariadb is connect and run succesed!"); mysql_close(con); return 0; }

具体的编译命令

su root gcc -Wall -ggdb2 -I/usr/include/mariadb -o mariadb_demo.out mariadb_demo.c -lmysqlclient ./mariadb_demo.out

运行结果如下

C基础 mariadb处理的简单实例4

到这里基本C 调用 MariaDB 基本流程跑通了. 但是很不爽. 只能通过root用户使用.

那我们改变这里不爽. 进入第二部分. 扩展资料 c in mariadb http://stackoverflow.com/questions/17265471/using-mariadb-in-c

第二部分 : 通过普通用户完成业务需求.

先创建普通用户 csz, 密码是 1413222, 并并且给其 select 读权限

su root mysql drop user csz; create user 'csz'@'%' identified by '13142222'; grant select on *.* to 'csz'@'%'; # 立即刷新 flush privileges;

后面登录试试

mysql -ucsz -p1314222 -h127.0.0.1

C基础 mariadb处理的简单实例5

主要是mariadb默认关闭远程访问. 后面我们开启安全访问模式试试

su root/etc/init.d/mysql stopmysqld_safe --skip-grant-tables

C基础 mariadb处理的简单实例6

后面再开启一个会话 . 重新输入 mysql -ucsz -p1314222 -h127.0.0.1 , 解决可以了

C基础 mariadb处理的简单实例7

#目标拼接串内容 select sum(c) from ( select count(*) as c from 2016_6_1_oss_musicelves where specifytype=1 and char_id = 30422720614402293 union all select count(*) from 2016_6_2_oss_musicelves where specifytype=1 and char_id = 30422720614402293 union all select count(*) from 2016_6_3_oss_musicelves where specifytype=1 and char_id = 30422720614402293 union all select count(*) from 2016_6_4_oss_musicelves where specifytype=1 and char_id = 30422720614402293 union all select count(*) from 2016_6_5_oss_musicelves where specifytype=1 and char_id = 30422720614402293 union all select count(*) from 2016_6_9_oss_musicelves where specifytype=1 and char_id = 30422720614402293 union all select count(*) from 2016_6_10_oss_musicelves where specifytype=1 and char_id = 30422720614402293 union all select count(*) from 2016_6_12_oss_musicelves where specifytype=1 and char_id = 30422720614402293 ) as t;

具体看 getmouths.c 文件内容

#include <stdio.h> #include <stdlib.h> #include <time.h> #include <mysql.h> #define _INT_BUF (4098) // 得到查询数据表内容 #define _STR_SQLTABLES "select distinct table_name from information_schema.columns where table_name like '%d_%d_%%_oss_musicelves'" #define _STR_SQLSELECT "select count(*) as c from %s where specifytype=1 and char_id = %lld" // 基础的mariadb 错误关闭函数 static inline void _err_mariadb(MYSQL *con) { fprintf(stderr, "_err_mariadb error: %sn", mysql_error(con)); mysql_close(con); exit(EXIT_FAILURE); } /* * 处理 oss_musicelves 一个月的所有表. */ int main(int argc, char* argv[]) { long long ptid; time_t rt = time(NULL); struct tm *pt = localtime(&rt); int year = pt->tm_year + 1900; int mouth = pt->tm_mon + 1; // 先简单检测输入 if(argc <= 1) { fprintf(stderr, "%s [ptid] [mouth] [year]n", argv[0]); exit(EXIT_FAILURE); } // 先得到 ptid 数据 ptid = atoll(argv[1]); // 得到当前月份 if(argc >= 3) mouth = atoi(argv[2]); // 得到当前年份 if(argc >= 4) year = atoi(argv[3]); // 简单检测结果是否合法 if(ptid < 0 || mouth <=0 || mouth>12 || year<1900) { fprintf(stderr, "%s %lld %d %d is error!n", argv[0], ptid, mouth, year); exit(EXIT_FAILURE); } // 输出结果 printf("%s %lld %d %d start run!n", argv[0], ptid, mouth, year); // 开始用mysql 访问我们需要访问的数据结果了 MYSQL *con = mysql_init(NULL); if(con == NULL) { fprintf(stderr, "mysql_init error: %sn", mysql_error(con)); exit(EXIT_FAILURE); } if(!mysql_real_connect(con, "127.0.0.1", "csz", "1314222", "oss_log", 0, NULL, 0)) _err_mariadb(con); char sqls[_INT_BUF]; int sqlen = 0; sprintf(sqls, _STR_SQLTABLES, year, mouth); if(mysql_query(con, sqls)) _err_mariadb(con); // 开始得到结果 MYSQL_RES *ret = mysql_store_result(con); if(NULL == ret) _err_mariadb(con); MYSQL_ROW row; int i = 0, nr = 0; while(!!(row = mysql_fetch_row(ret))) { if(i == 0) { sqlen = sprintf(sqls, "select sum(c) from (n" _STR_SQLSELECT, row[0], ptid); i = 1; continue; } // 后面正常拼接 nr = sprintf(sqls + sqlen, "nunion alln" _STR_SQLSELECT, row[0], ptid); if((sqlen += nr) >= _INT_BUF) { fprintf(stderr, "sprintf while %d too length.n", sqlen); goto __return_free; } } if(i == 0) { printf("sum %lld %d/%d: 0n", ptid, year, mouth); goto __return_free; } // 这里处理有的数据 nr = sprintf(sqls + sqlen, "n) as t;"); if((sqlen += nr) >= _INT_BUF) { fprintf(stderr, "sprintf end %d too length.n", sqlen); goto __return_free; } // 内存用完了就直接释放 mysql_free_result(ret); ret = NULL; printf("sql : nt%sn", sqls); // 开始输出统计结果 if(mysql_query(con, sqls)) _err_mariadb(con); if((ret = mysql_store_result(con))==NULL) _err_mariadb(con); //得到结果直接返回 if(!!(row=mysql_fetch_row(ret))) printf("sum %lld %d/%d: %sn", ptid, year, mouth, row[0]); else puts("select is empty!"); __return_free: // 释放用过的内存 mysql_free_result(ret); // 关闭打开的数据库访问对象 mysql_close(con); return 0; }

编译命令

gcc -Wall -ggdb2 -I/usr/include/mariadb -o getmouths.out getmouths.c -lmysqlclient

最终运行结果是

C基础 mariadb处理的简单实例8

如果想详细了解关于mariadb c驱动的api使用, 可以参照老外写的很好理解.

mysqlc demo http://zetcode.com/db/mysqlc/

到这里就结束了, 关于C 访问数据库能力也基本打通了.

后记

错误是难免, 欢迎学习进步~~~ 未来什么都不确定, 可以确定是没有未来, 只有现在还在装逼 .

以上这篇C基础 mariadb处理的简单实例就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持查字典教程网。