| 最近打算写一套OA系统，为了方便进行数据库操作，特意抽出一周的时间来研究C/C++访问各种数据库的方法，并打算封装一套数据库操作类，现在奉上最简单的一部分：在Linux下访问MySQL数据库。
本文中使用的MySQL API代码为C语言，如果各位对C++有兴趣，可以考虑使用mysql++。
一、配置开发环境
首先需要编译、安装MySQL，安装完成后，将MySQL目录中的lib目录添加到环境变量中。
新建C/C++工程，把$MYSQL_ROOT/include添加到编译环境的包含路径下面。在编译选项中，增加$MYSQL_ROOT/lib目录。在Link选项中增加-lmysqlclient（已经把lib目录增加到系统环境变量中），或者直接引用libmysqlclient.so文件。
二、程序代码
不多说了，直接上代码，注释都很详细。
/*
* MySQLManager.h
*
* Created on: Feb 18, 2009
* Author: Steven Wee
*/
#ifndef MYSQLMANAGER_H_
#define MYSQLMANAGER_H_
#include "../Common/CheckStringTools.h"
#include <mysql.h>
#include <string>
#include <iostream>
#include <vector>
#include <string.h>
using namespace std;
class MySQLManager
{
public:
/*
* Init MySQL
* @param hosts: Host IP address
* @param userName: Login UserName
* @param password: Login Password
* @param dbName: Database Name
* @param port: Host listen port number
*/
MySQLManager(std::string hosts, std::string userName, std::string password, std::string dbName, unsigned int port);
~MySQLManager();
void initConnection();
/*
* Making query from database
* @param mysql: MySQL Object
* @param sql: Running SQL command
*/
bool runSQLCommand(std::string sql);
/**
* Destroy MySQL object
* @param mysql MySQL object
*/
void destroyConnection();
bool getConnectionStatus();
vector< vector<string> > getResult();
protected:
void setUserName(std::string userName);
void setHosts(std::string hosts);
void setPassword(std::string password);
void setDBName(std::string dbName);
void setPort(unsigned int port);
private:
bool IsConnected;
vector< vector<string> > resultList;
MYSQL mySQLClient;
unsigned int DEFAULTPORT;
char * HOSTS;
char * USERNAME;
char * PASSWORD;
char * DBNAME;
};
#endif /* MYSQLMANAGER_H_ */
/*
* MySQLManager.cpp
*
* Created on: Feb 18, 2009
* Author: Steven Wee
*/
#include "MySQLManager.h"
MySQLManager::MySQLManager(string hosts, string userName, string password, string dbName, unsigned int port)
{
IsConnected = false;
this ->setHosts(hosts); // 设置主机IP地址
this ->setUserName(userName); // 设置登录用户名
this ->setPassword(password); // 设置登录密码
this ->setDBName(dbName); // 设置数据库名
this ->setPort(port); // 设置端口号
}
MySQLManager::~MySQLManager()
{
this ->destroyConnection();
}
void MySQLManager::setDBName(string dbName)
{
if ( dbName.empty() )
{// 用户没有指定数据库名
std::cout << "DBName is null! Used default value: mysql" << std::endl;
this ->DBNAME = new char[5];
strcpy(this ->DBNAME, "mysql");
}
else
{
this ->DBNAME = new char[dbName.length()];
strcpy(this ->DBNAME, dbName.c_str());
}
}
void MySQLManager::setHosts(string hosts)
{
if ( hosts.empty() )
{// 用户没有指定数据库IP地址
std::cout << "Hosts is null! Used default value: localhost" << std::endl;
this ->HOSTS = new char[9];
strcpy(this ->HOSTS, "localhost");
}
else
{
this ->HOSTS = new char[hosts.length()];
strcpy(this ->HOSTS, hosts.c_str());
}
}
void MySQLManager::setPassword(string password)
{// 用户没有指定密码
if ( password.empty() )
{
std::cout << "Password is null! Used default value: " << std::endl;
this ->PASSWORD = new char[1];
strcpy(this ->PASSWORD, "");
}
else
{
this ->PASSWORD = new char[password.length()];
strcpy(this ->PASSWORD, password.c_str());
}
}
void MySQLManager::setPort(unsigned int port)
{// 用户没有指定端口号，使用默认端口号
if ( port )
{
std::cout << "Port number is null! Used default value: 0" << std::endl;
this ->DEFAULTPORT = 0;
}
else
{
this ->DEFAULTPORT = port;
}
}
void MySQLManager::setUserName(string userName)
{// 用户没有指定登录用户名
if ( userName.empty() )
{
std::cout << "UserName is null! Used default value: root" << std::endl;
this ->USERNAME = new char[4];
strcpy(this ->USERNAME, "root");
}
else
{
this ->USERNAME = new char[userName.length()];
strcpy(this ->USERNAME, userName.c_str());
}
}
void MySQLManager::initConnection()
{
if ( IsConnected )
{// 已经连接到服务器
std::cout << "Is connected to server!" <<std::endl;
return;
}
mysql_init(&mySQLClient);// 初始化相关对象
if ( !mysql_real_connect( &mySQLClient, HOSTS, USERNAME, PASSWORD, DBNAME, DEFAULTPORT, NULL, 0) )
{// 连接到服务器
std::cout << "Error connection to database: %s/n" << mysql_error(&mySQLClient) << std::endl;
}
IsConnected = true;// 修改连接标识
}
bool MySQLManager::runSQLCommand(string sql)
{
if ( !IsConnected )
{// 没有连接到服务器
std::cout << "Not connect to database!" << std::endl;
return false;
}
if ( sql.empty() )
{// SQL语句为空
std::cout << "SQL is null!" << std::endl;
return false;
}
MYSQL_RES *res;
MYSQL_ROW row;
unsigned int i,j = 0;
StringTools stringTools;
sql = stringTools.filterString(sql);
i = mysql_real_query(&mySQLClient,sql.c_str(),(unsigned int)strlen(sql.c_str()));// 执行查询
if ( i )
{
std::cout << "Error query from database: %s/n" << mysql_error(&mySQLClient) << std::endl;
return false;
}
res = mysql_store_result(&mySQLClient);
vector<string> objectValue;
while( (row = mysql_fetch_row(res)) )
{// 遍历结果集
objectValue.clear();
for ( j = 0 ; j < mysql_num_fields(res) ; j++ )
{
objectValue.push_back(row[j]);
}
this ->resultList.push_back(objectValue);
}
mysql_free_result(res); //free result after you get the result
return true;
}
vector< vector<string> > MySQLManager::getResult()
{
return resultList;
}
void MySQLManager::destroyConnection()
{
mysql_close(&mySQLClient);
this ->IsConnected = false;
}
bool MySQLManager::getConnectionStatus()
{
return IsConnected;
}
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