Linux下编写C++服务器(MySQL连接)

其他 2020-01-14 11:56:31 阅读次数: 0

安装MySQL

网上有很多从yum下载安装的教程，但是不知道什么原因下载速度很慢，速度在10k/s以内，这里是参照CentOS 7离线安装MySQL 5.7下载的，操作比较复杂，但速度会快一点，觉得麻烦可以直接在yum下载。
安装完MySQL服务器后，我的C++程序使用MySQL的include和lib目录连接不上数据库，后面安装一个叫mysql-devel的一个驱动，并使用它的include和lib才连接成功，安装方法很简单，在终端输入

yum install mysql-devel

就可以安装了。

配置环境

  1. 安装完成后，会出现/usr/include/mysql和/usr/lib64/mysql，这里面包含了我们需要的头文件和库。
    把/usr/local/mysql/include/放到windows的共享目录下，并改名为mysql；
cp -r /usr/local/mysql/include/ /mnt/hgfs/LinuxShare/
mv /mnt/hgfs/LinuxShare/include/ /mnt/hgfs/LinuxShare/mysql
  1. 创建一个名为databaseTest的Makefile项目；
  2. 右键项目，选择属性，在General的Remote Build Root Directory中写入Linux上的项目目录，
    在这里插入图片描述
    在C++->Include Search Path添加E:\LinuxShare\include;E:\LinuxShare\include\c++\4.8.2;E:\LinuxShare\mysql;
    在这里插入图片描述
    在Remote Build四项中分别写入
cd $(RemoteRootDir)/$(ProjectName); make build
cd $(RemoteRootDir)/$(ProjectName); make clean build
cd $(RemoteRootDir)/$(ProjectName); make clean
$(RemoteRootDir)/$(ProjectName)/dbTest

如图：
在这里插入图片描述

  1. 在项目下添加main.cpp、Mysqlop.h、Mysql.cpp、Makefile，
    在这里插入图片描述
    这里我已经对SQL的操作进行了封装，
    Mysqlop.h
#pragma once

#include <mysql.h>
#include <errmsg.h>
#ifndef MYSQL_SUCCESSED
#define MYSQL_SUCCESSED			0					// 执行成功
#define MYSQL_CONNECT_NULL		CR_MAX_ERROR + 1	// 连接为空
#define MYSQL_MEMORY_ERROR		CR_MAX_ERROR + 2	// 内部存储空间不够
#define MYSQL_CONNECT_FAIL		CR_MAX_ERROR + 3	// sqlconnect失败
#define MYSQL_INIT_FAIL			CR_MAX_ERROR + 4	// sqlinit失败，一般为内存不够
#define MYSQL_QUERY_NEW_FAIL	CR_MAX_ERROR + 5	// sqlquery语句过长，动态申请空间不够
#define MYSQL_QUERY_MEMORY_FAIL	CR_MAX_ERROR + 6	// sqlquery语句过长，动态申请空间失败
#define MYSQL_CONTINUE			CR_MAX_ERROR + 7	// sql错误中断，但仍然可以继续
#define MYSQL_NOT_CONTINUE		CR_MAX_ERROR + 8	// sql错误中断，不可继续
#define MYSQL_SELCTDB_ERROR		CR_MAX_ERROR + 9	// 选择数据库失败
#define MYSQL_UNKNOWN_ERROR		CR_MAX_ERROR + 10	// 其它未知错误，可能是内部存储空间不够
#endif

class Mysqlop
{
public:
	Mysqlop();
	~Mysqlop();

protected:
	char ip[64];
	char username[256];
	char passwd[256];
	char dbname[256];
	unsigned int port;
	MYSQL* sql;
	char errmsg[1024];

public:
	int sqlconnect(const char* ip, unsigned int port, const char* username, const char* passwd, const char* dbname);
	int sqlconnect(void);
	bool isconnected(void);

	//选择修改数据库
	int sqlselectdb(const char*  dbname);
	int sqlselectdb(void);
	
	int sqlquery(const char* query);
	int sqlclose(void);
	unsigned long getinsertid(void);
	unsigned long sqlnumrows(MYSQL_RES* res);

	MYSQL_RES* sqlstoreresult(void);
	MYSQL_ROW sqlfetchrow(MYSQL_RES* sqlRes);
	void sqlfreeresult(MYSQL_RES* result);

	//测试数据库联通性，用于登录前的验证
	int testsqlconnect(const char* ip, unsigned int port, const char* username, const char* passwd, const char* dbname);

	char* geterrmsg();
};

Mysqlop.cpp

#include "Mysqlop.h"
#include <stdio.h>
#include <string.h>
#include <errno.h> 

Mysqlop::Mysqlop()
{
	sql = NULL;
	memset(ip, 0x00, sizeof(ip));
	memset(username, 0x00, sizeof(username));
	memset(passwd, 0x00, sizeof(passwd));
	memset(dbname, 0x00, sizeof(dbname));
	port = 0x00;
}


Mysqlop::~Mysqlop()
{
	if (sql != nullptr)
		sqlclose();
}

int Mysqlop::sqlconnect(const char * ip, unsigned int port, const char * username, const char * passwd, const char * dbname)
{
	if (nullptr == sql){
		sql = mysql_init(NULL);
	}
	if (nullptr == sql){
		snprintf(errmsg, sizeof(errmsg), "MySQL init error: %s\n", mysql_error(sql));
		return MYSQL_INIT_FAIL;
	}

	this->port = port;
	strncpy(this->ip,ip, sizeof(this->ip));
	strncpy(this->username, username, sizeof(this->username));
	strncpy(this->passwd, passwd, sizeof(this->passwd));
	strncpy(this->dbname, dbname, sizeof(this->dbname));

	if (!mysql_real_connect(sql, this->ip, this->username, this->passwd, this->dbname, this->port, NULL, 0)){
		snprintf(errmsg, sizeof(errmsg), "MySQL connect error: %s\n", mysql_error(sql));
		return MYSQL_CONNECT_FAIL;
	}
	else{ 
		char value = 1;
		mysql_options(sql, MYSQL_OPT_RECONNECT, &value);
		return MYSQL_SUCCESSED;
	}
		
}

int Mysqlop::sqlconnect(void)
{
	if (nullptr == sql){
		sql = mysql_init(NULL);
	}
	if (nullptr == sql){
		snprintf(errmsg, sizeof(errmsg), "MySQL init error: %s\n", mysql_error(sql));
		return MYSQL_INIT_FAIL;
	}

	if (this->ip && this->username && this->passwd && this->dbname && this->port > 0){
		if (!mysql_real_connect(sql, this->ip, this->username, this->passwd, this->dbname, this->port, NULL, 0)){
			snprintf(errmsg, sizeof(errmsg), "MySQL connect error: %s\n", mysql_error(sql));
			return MYSQL_CONNECT_FAIL;
		}
		else{
			char value = 1;
			mysql_options(sql, MYSQL_OPT_RECONNECT, &value);
			return MYSQL_SUCCESSED;
		}
	}
	else {
		snprintf(errmsg, sizeof(errmsg), "MySQL connect parameter error\n");
		return MYSQL_MEMORY_ERROR;
	}
}

bool Mysqlop::isconnected(void)
{
	if (nullptr == sql)
		return false;
	//没连会自动重连
	int retCode = mysql_ping(sql);
	if (retCode)
		return false;
	else
		return true;
}

int Mysqlop::sqlselectdb(const char * dbname)
{
	if (sql == nullptr)
		sqlconnect();
	int ret = mysql_select_db(sql, dbname);
	if (ret){
		snprintf(errmsg, sizeof(errmsg), "MySQL select database error: %s\n", mysql_error(sql));
		return MYSQL_SELCTDB_ERROR;
	}
	else
		return MYSQL_SUCCESSED;
}

int Mysqlop::sqlselectdb(void)
{
	if (sql != nullptr)
		sqlclose();

	if (sqlconnect() != MYSQL_SUCCESSED)
		return MYSQL_CONNECT_FAIL;

	int ret = mysql_select_db(sql, dbname);
	if (ret) {
		snprintf(errmsg, sizeof(errmsg), "MySQL select database error: %s\n", mysql_error(sql));
		return MYSQL_SELCTDB_ERROR;
	}
	else
		return MYSQL_SUCCESSED;
}

int Mysqlop::sqlquery(const char * query)
{
	if(query[0] == 0x00)
		return MYSQL_SUCCESSED;
	if (sql == NULL){
		sqlclose();
		sqlconnect();	// 尝试重连
	}

	int retCode = mysql_ping(sql);  
	if (retCode){
		sqlclose();
		sqlconnect();
	}
	
	retCode = mysql_real_query(sql, query, (unsigned long)strlen(query));
	if (retCode){
		snprintf(errmsg, sizeof(errmsg), "MySQL query error: %s\n", mysql_error(sql));
		return MYSQL_UNKNOWN_ERROR;
	}
	else
		return MYSQL_SUCCESSED;
}

int Mysqlop::sqlclose(void)
{
	if (sql != nullptr){
		mysql_close(sql);
		sql = nullptr;
	}
	return MYSQL_SUCCESSED;
}

unsigned long Mysqlop::getinsertid(void)
{
	return (unsigned long)mysql_insert_id(sql);
}

unsigned long Mysqlop::sqlnumrows(MYSQL_RES * res)
{
	return (unsigned long)mysql_num_rows(res);
}

MYSQL_RES * Mysqlop::sqlstoreresult(void)
{
	return mysql_store_result(sql);
}

MYSQL_ROW Mysqlop::sqlfetchrow(MYSQL_RES * sqlRes)
{
	if (!sqlRes) 
		return NULL;
	return mysql_fetch_row(sqlRes);
}

void Mysqlop::sqlfreeresult(MYSQL_RES * result)
{
	mysql_free_result(result);
}

int Mysqlop::testsqlconnect(const char * ip, unsigned int port, const char * username, const char * passwd, const char * dbname)
{
	int ret = 0;

	if (NULL == sql)
	{
		sql = mysql_init(NULL);
	}
	if (NULL == sql)
	{
		return MYSQL_INIT_FAIL;
	}

	this->port = port;
	strncpy(this->ip, ip, sizeof(this->ip));
	strncpy(this->username, username, sizeof(this->username));
	strncpy(this->passwd, passwd, sizeof(this->passwd));
	strncpy(this->dbname, dbname, sizeof(this->dbname));

	//连接数据库
	if (!mysql_real_connect(sql, this->ip, this->username, this->passwd, this->dbname, this->port, NULL, 0)) {
		snprintf(errmsg, sizeof(errmsg), "MySQL connect error: %s\n", mysql_error(sql));
		return MYSQL_CONNECT_FAIL;
	}
	else {
		//连接成功，测试数据库
		ret = mysql_select_db(sql, this->dbname);
		if (ret) {
			sqlclose();	//断开连接
			return MYSQL_SELCTDB_ERROR;
		}
		else {
			sqlclose();	//断开连接
			return MYSQL_SUCCESSED;
		}
	}
}

char * Mysqlop::geterrmsg()
{
	return errmsg;
}

main.cpp

#pragma once
#pragma execution_character_set("utf-8")
#include <iostream>
#include <stdio.h>
#include <string.h>
#include "Mysqlop.h"
int main(int argc, char *argv[])
{
	Mysqlop mysql;
	int ret = MYSQL_SUCCESSED;

	ret = mysql.testsqlconnect("127.0.0.1", 3306, "root", "123456", "test");
	if (ret != MYSQL_SUCCESSED) {
		std::cout << mysql.geterrmsg();
		return 0;
	}

	ret = mysql.sqlconnect();
	if (ret != MYSQL_SUCCESSED) {
		std::cout << mysql.geterrmsg();
		return 0;
	}
	//创表
	char query[1024] = { 0 };
	strcpy(query, "create table if not exists `student`(\
							`id` int unsigned auto_increment,\
							`name` varchar(100) not null,\
							`age` int unsigned not null,\
							primary key (`id`)\
							)ENGINE=InnoDB DEFAULT CHARSET=utf8;");
	ret = mysql.sqlquery(query);
	if (ret != MYSQL_SUCCESSED) {
		std::cout << mysql.geterrmsg();
		return 0;
	}
	//清表
	strcpy(query, "truncate table student;");
	ret = mysql.sqlquery(query);
	if (ret != MYSQL_SUCCESSED) {
		std::cout << mysql.geterrmsg();
		return 0;
	}
	//插表
	strcpy(query, "insert into student(name, age)values('张三',12),('李四',13),('小明',15),('小刚',15);");
	ret = mysql.sqlquery(query);
	if (ret != MYSQL_SUCCESSED) {
		std::cout << mysql.geterrmsg();
		return 0;
	}
	//查表
	MYSQL_RES *sqlres;
	MYSQL_ROW sqlrow;
	snprintf(query, sizeof(query), "select id,name from student where age=%d;",15 );
	ret = mysql.sqlquery(query);
	if (ret != MYSQL_SUCCESSED) {
		std::cout << mysql.geterrmsg();
		return 0;
	}
	sqlres = mysql.sqlstoreresult();
	while ((sqlrow = mysql.sqlfetchrow(sqlres)) != NULL)
	{
		if (sqlrow[0] && sqlrow[1])
		{
			std::cout << "id:" << sqlrow[0] << ",姓名:" << sqlrow[1] << std::endl;
		}
	}
	mysql.sqlfreeresult(sqlres);
	mysql.sqlclose();
	return 0;
}

Makefile

INCLUDEPATH=/usr/include/mysql
LIBPATH=/usr/lib64/mysql
CC1=g++

build:main.o Mysqlop.o
	$(CC1) -gdwarf-2 -o dbTest main.o Mysqlop.o -std=c++11 -I $(INCLUDEPATH) -L $(LIBPATH) -lmysqlclient

main.o:main.cpp Mysqlop.h
	$(CC1) -gdwarf-2 -c main.cpp -std=c++11 -I $(INCLUDEPATH) -L $(LIBPATH) -lmysqlclient

Mysqlop.o:Mysqlop.cpp Mysqlop.h
	$(CC1) -gdwarf-2 -c Mysqlop.cpp -std=c++11 -I $(INCLUDEPATH) -L $(LIBPATH) -lmysqlclient

clean:
	rm *.o dbTest

运行

在这里插入图片描述

小学狗喵喵叫
发布了14 篇原创文章 · 获赞 6 · 访问量 3121
私信 关注

猜你喜欢

转载自blog.csdn.net/qq_39554698/article/details/98739440
今日推荐
TIOBE 5 月榜单：Fortran “复活”进入 Top 10
GCC 14.1 发布
面壁智能发布 Eurux-8x22B 开源大模型 —— 堪称「理科状元」
开源日报 | 谷歌扶持鸿蒙上位；开源Rabbit R1；Docker加持的安卓手机；微软的焦虑和野心；海尔电器把开放平台关了
中国码农的“35岁魔咒”
蘭雅 CorelDRAW 插件 2024.5.1 国际劳动节版，免费下载
Arc Browser for Windows 1.0 正式 GA
90后程序员开发视频搬运软件、不到一年获利超 700 万，结局很刑！
周排行
Java自定义时间格式
同步整形电路
在开发中最最最常用的字符串的属性大集合
Linux 查看端口占用并杀掉
Java基础四：ArrayList
多线程之死锁就是这么简单
mysql 基础命令集
awk 命令详解
Centos6.3编译安装nginx+php步骤
OCR （Optical Character Recognition，光学字符识别）
每日归档
更多
2024-05-08(42)
2024-05-07(14)
2024-05-06(40)
2024-05-05(0)
2024-05-04(7)
2024-05-03(19)
2024-05-02(0)
2024-05-01(4)
2024-04-30(1)
2024-04-29(40)

代码天地 © 2018 codetd.com

境外服务器   最新电视剧2022