C基础 mariadb处理简单案例

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

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

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

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, "%s
", mysql_error(con));
        exit(EXIT_FAILURE);
      }

      if (!mysql_real_connect(con, "localhost", "root", "", NULL, 0, NULL, 0)) {
        fprintf(stderr, "%s
", mysql_error(con));
         mysql_close(con);
         exit(EXIT_FAILURE);
      }  

      if (mysql_query(con, "show databases;")) {
        fprintf(stderr, "%s
", 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 

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

 

 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 stop
mysqld_safe --skip-grant-tables

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
 

到这里 通过新建的 csz 用户访问成功. 好了. 那我们开始写一个 msyql c 代码处理我们的业务. 按照月来访问. 那我们开始写代码.代码的总的思路是拼接一个这样的串

#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: %s
", 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]
", 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!
", argv[0], ptid, mouth, year);
        exit(EXIT_FAILURE);
    } 

    // 输出结果
    printf("%s %lld %d %d start run!
", 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: %s
", 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 (
" _STR_SQLSELECT, row[0], ptid);
            i = 1;
            continue;
        }        
        // 后面正常拼接
        nr = sprintf(sqls + sqlen, "
union all
" _STR_SQLSELECT, row[0], ptid);
        if((sqlen += nr) >= _INT_BUF) {
            fprintf(stderr, "sprintf while %d too length.
", sqlen);
            goto __return_free;
        }
    }
    if(i == 0)     {
        printf("sum %lld %d/%d: 0
", ptid, year, mouth);
        goto __return_free;
    }
    
    // 这里处理有的数据
    nr = sprintf(sqls + sqlen, "
) as t;");    
    if((sqlen += nr) >= _INT_BUF) {
        fprintf(stderr, "sprintf end %d too length.
", sqlen);
        goto __return_free;
    }
    // 内存用完了就直接释放
    mysql_free_result(ret);
    ret = NULL;
    

    printf("sql : 
	%s
", 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: %s
", 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

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 . 

后面经过实践 找到更好的解决方案 采用 mysql 存储过程

-- 最终结果令人满意, mysql存储过程
delimiter $$
drop procedure if exists oss_log.proc_oss_monopolycollect;
-- yr:年份, mh:月份, qq:查询QQ号, cut:输出当月统计的个数
create procedure oss_log.proc_oss_monopolycollect(in yr int, in mh int, in qq int, out cut int)
begin
    set @ltname = concat(yr, '_', mh , '_%_oss_monopolycollect');
    
    select replace(
            group_concat(distinct(table_name)),
            ',',
            ' where specifytype = 1 and account_id = {account_id} union all select count(*) from oss_log.'
            ) into @sqlstr
    from information_schema.columns where table_name like @ltname;
    
    -- 添加前面和尾巴部分
    set @sqlstr = concat('select sum(c) into @sumc from (select count(*) as c from oss_log.', 
                         @sqlstr,
                         ' where specifytype = 1 and account_id = {account_id}) as t;');
    -- 替换占位符, 得到最终的串内容
    set @sqlstr = replace(@sqlstr, "{account_id}", qq);
    
    -- 预编译并执行
    prepare stmt from @sqlstr;
    -- 开始执行
    execute stmt;
    -- 删除预编译的结果
    deallocate prepare stmt;
    
    -- 返回结果
    set cut = @sumc;
end
$$
delimiter ;

测试 脚本 如下

-- 测试上面存储过程
call oss_log.proc_oss_monopolycollect(2016, 5, 9331453, @cut);
select @cut;
set @cut:=NULL;
drop procedure if exists oss_log.proc_oss_monopolycollect

 这里基本就解决 遇到的问题. 最后想说一句, 真jb长!