C++利用MySQL API连接和操作数据库实例详解

//mysqlhelper.h#ifndef __MYSQL_HELPER_H__#define __MYSQL_HELPER_H__#include <stdlib.h>#include <map>#include <vector>#include <string>using namespace std;#include <mysql.h>namespace mysqlhelper{/**********************@brief 数据库异常类**********************/struct MysqlHelper_Exception //: public TC_Exception{ MysqlHelper_Exception(const string &sBuffer):errorInfo(sBuffer){}; //: TC_Exception(sBuffer){}; ~MysqlHelper_Exception() throw(){};  string errorInfo;};/************************ @brief 数据库配置接口***********************/struct DBConf{ string _host;//主机地址 string _user; //用户名  string _password;//密码 string _database; //数据库 string _charset; //字符集 int _port;//端口 int _flag; //客户端标识 /***************** * @brief 构造函数 *****************/ DBConf():_port(0), _flag(0){} /********************************** * @brief 读取数据库配置.  * @param mpParam 存放数据库配置的map  * dbhost: 主机地址 * dbuser:用户名 * dbpass:密码 * dbname:数据库名称 * dbport:端口 **********************************/ void loadFromMap(const map<string, string> &mpParam) { map<string, string> mpTmp = mpParam; _host = mpTmp["dbhost"]; _user = mpTmp["dbuser"]; _password = mpTmp["dbpass"]; _database = mpTmp["dbname"]; _charset = mpTmp["charset"]; _port = atoi(mpTmp["dbport"].c_str()); _flag = 0; if(mpTmp["dbport"] == "") { _port = 3306; } }};/*************************************************************** @brief:MySQL数据库操作类 * @feature:非线程安全，通常一个线程一个MysqlHelper对象；* 对于insert/update可以有更好的函数封装，保证SQL注入；* MysqlHelper::DB_INT表示组装sql语句时，不加””和转义；* MysqlHelper::DB_STR表示组装sql语句时，加””并转义；**************************************************************/class MysqlHelper{public: /** * @brief 构造函数 */ MysqlHelper(); /** * @brief 构造函数.  * @param: sHost:主机IP * @param sUser 用户 * @param sPasswd 密码 * @param sDatebase 数据库 * @param port 端口 * @param iUnixSocket socket * @param iFlag 客户端标识 */ MysqlHelper(const string& sHost, const string& sUser = "", const string& sPasswd = "", const string& sDatabase = "", const string &sCharSet = "", int port = 0, int iFlag = 0); /** * @brief 构造函数.  * @param tcDBConf 数据库配置 */ MysqlHelper(const DBConf& tcDBConf); /** * @brief 析构函数. */ ~MysqlHelper(); /** * @brief 初始化.  *  * @param sHost 主机IP * @param sUser 用户 * @param sPasswd 密码 * @param sDatebase 数据库 * @param port 端口 * @param iUnixSocket socket * @param iFlag 客户端标识 * @return 无 */ void init(const string& sHost, const string& sUser = "", const string& sPasswd = "", const string& sDatabase = "", const string &sCharSet = "", int port = 0, int iFlag = 0); /** * @brief 初始化.  *  * @param tcDBConf 数据库配置 */ void init(const DBConf& tcDBConf); /** * @brief 连接数据库.  *  * @throws MysqlHelper_Exception * @return 无 */ void connect(); /** * @brief 断开数据库连接.  * @return 无 */ void disconnect(); /** * @brief 获取数据库变量.  * @return 数据库变量 */ string getVariables(const string &sName); /** * @brief 直接获取数据库指针.  *  * @return MYSQL* 数据库指针 */ MYSQL *getMysql(); /** * @brief 字符转义.  *  * @param sFrom 源字符串 * @param sTo 输出字符串 * @return 输出字符串 */ string escapeString(const string& sFrom); /** * @brief 更新或者插入数据.  *  * @param sSql sql语句 * @throws MysqlHelper_Exception * @return */ void execute(const string& sSql); /** * @brief mysql的一条记录 */ class MysqlRecord { public: /** * @brief 构造函数. *  * @param record */ MysqlRecord(const map<string, string> &record); /** * @brief 获取数据，s一般是指数据表的某个字段名  * @param s 要获取的字段 * @return 符合查询条件的记录的s字段名 */ const string& operator[](const string &s); protected: const map<string, string> &_record; }; /** * @brief 查询出来的mysql数据 */ class MysqlData { public: /** * @brief 所有数据. *  * @return vector<map<string,string>>& */ vector<map<string, string> >& data(); /** * 数据的记录条数 *  * @return size_t */ size_t size(); /** * @brief 获取某一条记录.  *  * @param i 要获取第几条记录  * @return MysqlRecord类型的数据，可以根据字段获取相关信息， */ MysqlRecord operator[](size_t i); protected: vector<map<string, string> > _data; }; /** * @brief Query Record.  *  * @param sSql sql语句 * @throws MysqlHelper_Exception * @return MysqlData类型的数据，可以根据字段获取相关信息 */ MysqlData queryRecord(const string& sSql); /** * @brief 定义字段类型，  * DB_INT:数字类型  * DB_STR:字符串类型 */ enum FT { DB_INT,  DB_STR,  }; /** * 数据记录 */ typedef map<string, pair<FT, string> > RECORD_DATA; /** * @brief 更新记录.  *  * @param sTableName 表名 * @param mpColumns 列名/值对 * @param sCondition where子语句,例如:where A = B * @throws MysqlHelper_Exception * @return size_t 影响的行数 */ size_t updateRecord(const string &sTableName, const map<string, pair<FT, string> > &mpColumns, const string &sCondition); /** * @brief 插入记录.  *  * @param sTableName 表名 * @param mpColumns 列名/值对 * @throws MysqlHelper_Exception * @return size_t 影响的行数 */ size_t insertRecord(const string &sTableName, const map<string, pair<FT, string> > &mpColumns); /** * @brief 替换记录.  *  * @param sTableName 表名 * @param mpColumns 列名/值对 * @throws MysqlHelper_Exception * @return size_t 影响的行数 */ size_t replaceRecord(const string &sTableName, const map<string, pair<FT, string> > &mpColumns); /** * @brief 删除记录.  *  * @param sTableName 表名 * @param sCondition where子语句,例如:where A = B * @throws MysqlHelper_Exception * @return size_t 影响的行数 */ size_t deleteRecord(const string &sTableName, const string &sCondition = ""); /** * @brief 获取Table查询结果的数目.  *  * @param sTableName 用于查询的表名 * @param sCondition where子语句,例如:where A = B * @throws MysqlHelper_Exception * @return size_t 查询的记录数目 */ size_t getRecordCount(const string& sTableName, const string &sCondition = ""); /** * @brief 获取Sql返回结果集的个数.  *  * @param sCondition where子语句,例如:where A = B * @throws MysqlHelper_Exception * @return 查询的记录数目 */ size_t getSqlCount(const string &sCondition = ""); /** * @brief 存在记录.  *  * @param sql sql语句 * @throws MysqlHelper_Exception * @return 操作是否成功 */ bool existRecord(const string& sql); /** * @brief 获取字段最大值.  *  * @param sTableName 用于查询的表名 * @param sFieldName 用于查询的字段 * @param sCondition where子语句,例如:where A = B * @throws MysqlHelper_Exception * @return 查询的记录数目 */ int getMaxValue(const string& sTableName, const string& sFieldName, const string &sCondition = ""); /** * @brief 获取auto_increment最后插入得ID.  *  * @return ID值 */ long lastInsertID(); /** * @brief 构造Insert-SQL语句.  *  * @param sTableName 表名 * @param mpColumns 列名/值对 * @return string insert-SQL语句 */ string buildInsertSQL(const string &sTableName, const map<string, pair<FT, string> > &mpColumns); /** * @brief 构造Replace-SQL语句.  *  * @param sTableName 表名 * @param mpColumns 列名/值对 * @return string insert-SQL语句 */ string buildReplaceSQL(const string &sTableName, const map<string, pair<FT, string> > &mpColumns); /** * @brief 构造Update-SQL语句.  *  * @param sTableName 表名 * @param mpColumns 列名/值对 * @param sCondition where子语句 * @return string Update-SQL语句 */ string buildUpdateSQL(const string &sTableName,const map<string, pair<FT, string> > &mpColumns, const string &sCondition); /** * @brief 获取最后执行的SQL语句. *  * @return SQL语句 */ string getLastSQL() { return _sLastSql; } /** * @brief 获取查询影响数 * @return int */ size_t getAffectedRows();protected: /** * @brief copy contructor，只申明,不定义,保证不被使用  */ MysqlHelper(const MysqlHelper &tcMysql); /** *  * @brief 只申明,不定义,保证不被使用 */ MysqlHelper &operator=(const MysqlHelper &tcMysql);private: /** * 数据库指针 */ MYSQL *_pstMql; /** * 数据库配置 */ DBConf _dbConf; /** * 是否已经连接 */ bool _bConnected; /** * 最后执行的sql */ string _sLastSql;};}#endif //__MYSQL_HELPER_H__

//mysqlhelper.cpp#include "mysqlHelper.h"#include <string.h>#include <sstream>using namespace std;namespace mysqlhelper{MysqlHelper::MysqlHelper():_bConnected(false){ _pstMql = mysql_init(NULL);}MysqlHelper::MysqlHelper(const string& sHost, const string& sUser, const string& sPasswd, const string& sDatabase, const string &sCharSet, int port, int iFlag):_bConnected(false){ init(sHost, sUser, sPasswd, sDatabase, sCharSet, port, iFlag); _pstMql = mysql_init(NULL);}MysqlHelper::MysqlHelper(const DBConf& tcDBConf):_bConnected(false){ _dbConf = tcDBConf; _pstMql = mysql_init(NULL); }MysqlHelper::~MysqlHelper(){ if (_pstMql != NULL) { mysql_close(_pstMql); _pstMql = NULL; }}void MysqlHelper::init(const string& sHost, const string& sUser, const string& sPasswd, const string& sDatabase, const string &sCharSet, int port, int iFlag){ _dbConf._host = sHost; _dbConf._user = sUser; _dbConf._password = sPasswd; _dbConf._database = sDatabase; _dbConf._charset = sCharSet; _dbConf._port = port; _dbConf._flag = iFlag;}void MysqlHelper::init(const DBConf& tcDBConf){ _dbConf = tcDBConf;}void MysqlHelper::connect(){ disconnect(); if( _pstMql == NULL) { _pstMql = mysql_init(NULL); } //建立连接后, 自动调用设置字符集语句 if(!_dbConf._charset.empty()) { if (mysql_options(_pstMql, MYSQL_SET_CHARSET_NAME, _dbConf._charset.c_str())) { throw MysqlHelper_Exception(string("MysqlHelper::connect: mysql_options MYSQL_SET_CHARSET_NAME ") + _dbConf._charset + ":" + string(mysql_error(_pstMql))); } } if (mysql_real_connect(_pstMql, _dbConf._host.c_str(), _dbConf._user.c_str(), _dbConf._password.c_str(), _dbConf._database.c_str(), _dbConf._port, NULL, _dbConf._flag) == NULL)  { throw MysqlHelper_Exception("[MysqlHelper::connect]: mysql_real_connect: " + string(mysql_error(_pstMql))); } _bConnected = true;}void MysqlHelper::disconnect(){ if (_pstMql != NULL) { mysql_close(_pstMql); _pstMql = mysql_init(NULL); } _bConnected = false; }string MysqlHelper::escapeString(const string& sFrom){ if(!_bConnected) { connect(); } string sTo; string::size_type iLen = sFrom.length() * 2 + 1; char *pTo = (char *)malloc(iLen); memset(pTo, 0x00, iLen); mysql_real_escape_string(_pstMql, pTo, sFrom.c_str(), sFrom.length()); sTo = pTo; free(pTo); return sTo;}MYSQL *MysqlHelper::getMysql(void){ return _pstMql;}string MysqlHelper::buildInsertSQL(const string &sTableName, const RECORD_DATA &mpColumns){ ostringstream sColumnNames; ostringstream sColumnValues; map<string, pair<FT, string> >::const_iterator itEnd = mpColumns.end(); for(map<string, pair<FT, string> >::const_iterator it = mpColumns.begin(); it != itEnd; ++it) { if (it == mpColumns.begin()) { sColumnNames << "`" << it->first << "`"; if(it->second.first == DB_INT) { sColumnValues << it->second.second; } else { sColumnValues << "'" << escapeString(it->second.second) << "'"; } } else { sColumnNames << ",`" << it->first << "`"; if(it->second.first == DB_INT) { sColumnValues << "," + it->second.second; } else { sColumnValues << ",'" + escapeString(it->second.second) << "'"; } } } ostringstream os; os << "insert into " << sTableName << " (" << sColumnNames.str() << ") values (" << sColumnValues.str() << ")"; return os.str();}string MysqlHelper::buildReplaceSQL(const string &sTableName, const RECORD_DATA &mpColumns){ ostringstream sColumnNames; ostringstream sColumnValues; map<string, pair<FT, string> >::const_iterator itEnd = mpColumns.end(); for(map<string, pair<FT, string> >::const_iterator it = mpColumns.begin(); it != itEnd; ++it) { if (it == mpColumns.begin()) { sColumnNames << "`" << it->first << "`"; if(it->second.first == DB_INT) { sColumnValues << it->second.second; } else { sColumnValues << "'" << escapeString(it->second.second) << "'"; } } else { sColumnNames << ",`" << it->first << "`"; if(it->second.first == DB_INT) { sColumnValues << "," + it->second.second; } else { sColumnValues << ",'" << escapeString(it->second.second) << "'"; } } } ostringstream os; os << "replace into " << sTableName << " (" << sColumnNames.str() << ") values (" << sColumnValues.str() << ")"; return os.str();}string MysqlHelper::buildUpdateSQL(const string &sTableName,const RECORD_DATA &mpColumns, const string &sWhereFilter){ ostringstream sColumnNameValueSet; map<string, pair<FT, string> >::const_iterator itEnd = mpColumns.end(); for(map<string, pair<FT, string> >::const_iterator it = mpColumns.begin(); it != itEnd; ++it) { if (it == mpColumns.begin()) { sColumnNameValueSet << "`" << it->first << "`"; } else { sColumnNameValueSet << ",`" << it->first << "`"; } if(it->second.first == DB_INT) { sColumnNameValueSet << "= " << it->second.second; } else { sColumnNameValueSet << "= '" << escapeString(it->second.second) << "'"; } } ostringstream os; os << "update " << sTableName << " set " << sColumnNameValueSet.str() << " " << sWhereFilter; return os.str();}string MysqlHelper::getVariables(const string &sName){ string sql = "SHOW VARIABLES LIKE '" + sName + "'"; MysqlData data = queryRecord(sql); if(data.size() == 0) { return ""; } if(sName == data[0]["Variable_name"]) { return data[0]["Value"]; } return "";}void MysqlHelper::execute(const string& sSql){ /** 没有连上, 连接数据库 */ if(!_bConnected) { connect(); } _sLastSql = sSql; int iRet = mysql_real_query(_pstMql, sSql.c_str(), sSql.length()); if(iRet != 0) { /** 自动重新连接 */ int iErrno = mysql_errno(_pstMql); if (iErrno == 2013 || iErrno == 2006) { connect(); iRet = mysql_real_query(_pstMql, sSql.c_str(), sSql.length()); } } if (iRet != 0) { throw MysqlHelper_Exception("[MysqlHelper::execute]: mysql_query: [ " + sSql+" ] :" + string(mysql_error(_pstMql)));  }}MysqlHelper::MysqlData MysqlHelper::queryRecord(const string& sSql){ MysqlData data; /** 没有连上, 连接数据库 */ if(!_bConnected) { connect(); } _sLastSql = sSql; int iRet = mysql_real_query(_pstMql, sSql.c_str(), sSql.length()); if(iRet != 0) { /** 自动重新连接 */ int iErrno = mysql_errno(_pstMql); if (iErrno == 2013 || iErrno == 2006) { connect(); iRet = mysql_real_query(_pstMql, sSql.c_str(), sSql.length()); } } if (iRet != 0) { throw MysqlHelper_Exception("[MysqlHelper::execute]: mysql_query: [ " + sSql+" ] :" + string(mysql_error(_pstMql)));  } MYSQL_RES *pstRes = mysql_store_result(_pstMql); if(pstRes == NULL) { throw MysqlHelper_Exception("[MysqlHelper::queryRecord]: mysql_store_result: " + sSql + " : " + string(mysql_error(_pstMql))); } vector<string> vtFields; MYSQL_FIELD *field; while((field = mysql_fetch_field(pstRes))) { vtFields.push_back(field->name); } map<string, string> mpRow; MYSQL_ROW stRow; while((stRow = mysql_fetch_row(pstRes)) != (MYSQL_ROW)NULL) { mpRow.clear(); unsigned long * lengths = mysql_fetch_lengths(pstRes); for(size_t i = 0; i < vtFields.size(); i++) { if(stRow[i]) { mpRow[vtFields[i]] = string(stRow[i], lengths[i]); } else { mpRow[vtFields[i]] = ""; } } data.data().push_back(mpRow); } mysql_free_result(pstRes); return data;}size_t MysqlHelper::updateRecord(const string &sTableName, const RECORD_DATA &mpColumns, const string &sCondition){ string sSql = buildUpdateSQL(sTableName, mpColumns, sCondition); execute(sSql); return mysql_affected_rows(_pstMql);}size_t MysqlHelper::insertRecord(const string &sTableName, const RECORD_DATA &mpColumns){ string sSql = buildInsertSQL(sTableName, mpColumns); execute(sSql); return mysql_affected_rows(_pstMql);}size_t MysqlHelper::replaceRecord(const string &sTableName, const RECORD_DATA &mpColumns){ string sSql = buildReplaceSQL(sTableName, mpColumns); execute(sSql); return mysql_affected_rows(_pstMql);}size_t MysqlHelper::deleteRecord(const string &sTableName, const string &sCondition){ ostringstream sSql; sSql << "delete from " << sTableName << " " << sCondition; execute(sSql.str()); return mysql_affected_rows(_pstMql);}size_t MysqlHelper::getRecordCount(const string& sTableName, const string &sCondition){ ostringstream sSql; sSql << "select count(*) as num from " << sTableName << " " << sCondition; MysqlData data = queryRecord(sSql.str()); long n = atol(data[0]["num"].c_str()); return n;}size_t MysqlHelper::getSqlCount(const string &sCondition){ ostringstream sSql; sSql << "select count(*) as num " << sCondition; MysqlData data = queryRecord(sSql.str()); long n = atol(data[0]["num"].c_str()); return n;}int MysqlHelper::getMaxValue(const string& sTableName, const string& sFieldName,const string &sCondition){ ostringstream sSql; sSql << "select " << sFieldName << " as f from " << sTableName << " " << sCondition << " order by f desc limit 1"; MysqlData data = queryRecord(sSql.str()); int n = 0; if(data.size() == 0) { n = 0; } else { n = atol(data[0]["f"].c_str()); } return n;}bool MysqlHelper::existRecord(const string& sql){ return queryRecord(sql).size() > 0;}long MysqlHelper::lastInsertID(){ return mysql_insert_id(_pstMql);}size_t MysqlHelper::getAffectedRows(){ return mysql_affected_rows(_pstMql);}//////////////////////////////////////////////////////////////////////////////////////////////////////////////MysqlHelper::MysqlRecord::MysqlRecord(const map<string, string> &record):_record(record){}const string& MysqlHelper::MysqlRecord::operator[](const string &s){ map<string, string>::const_iterator it = _record.find(s); if(it == _record.end()) { throw MysqlHelper_Exception("field '" + s + "' not exists."); } return it->second;}//////////////////////////////////////////////////////////////////////////////////////////////////////////////vector<map<string, string> >& MysqlHelper::MysqlData::data(){ return _data;}size_t MysqlHelper::MysqlData::size(){ return _data.size();}MysqlHelper::MysqlRecord MysqlHelper::MysqlData::operator[](size_t i){ return MysqlRecord(_data[i]);}}//end namespace 

/*****************************************************@brief:mysqlhelper demo*@autor:lvlv*@date:2016.06.12*@MySQL version:MySQL Community Server 5.6.30 (GPL)****************************************************/#include <string.h>#include <iostream>#include <string>using namespace std;#include "mysqlHelper.h"using namespace mysqlhelper;int main(int argc,char* argv[]){ //初始化mysql对象并建立连接 MysqlHelper mysqlHelper; mysqlHelper.init("119.29.184.114","root","123456","StudentCourse"); try{ mysqlHelper.connect(); }catch(MysqlHelper_Exception& excep){ cout<<excep.errorInfo; return -1; } //增加一条学生记录 //示例插入语句 //string sql="insert into student values("201421031060","吕吕","华南理工大学","2014","软件工程",1)"; MysqlHelper::RECORD_DATA record; record.insert(make_pair("studentNo",make_pair(MysqlHelper::DB_STR,"201421031060"))); record.insert(make_pair("name",make_pair(MysqlHelper::DB_STR,"吕吕"))); record.insert(make_pair("school",make_pair(MysqlHelper::DB_STR,"广州中医药大学"))); record.insert(make_pair("grade",make_pair(MysqlHelper::DB_STR,"2014"))); record.insert(make_pair("major",make_pair(MysqlHelper::DB_STR,"计算机科学与技术"))); record.insert(make_pair("gender",make_pair(MysqlHelper::DB_INT,"1"))); int res=0; try{ res=mysqlHelper.insertRecord("student",record); }catch(MysqlHelper_Exception& excep){ cout<<excep.errorInfo; return -1; } cout<<"res:"<<res<<" insert successfully "<<endl; //删除一条学生记录，学号为201421031059 try{ res=mysqlHelper.deleteRecord("student","where studentNo=/"201421031059/""); }catch(MysqlHelper_Exception& excep){ cout<<excep.errorInfo; return -1; } cout<<"res:"<<res<<" delete successfully "<<endl; //查找学号为201421031059的学生选择的所有课程名称 MysqlHelper::MysqlData dataSet; string querySQL="select courseName from course co where co.courseNo in (select courseNo from courseSelection where studentNo=/"201421031060/")"; try{ dataSet=mysqlHelper.queryRecord(querySQL); }catch(MysqlHelper_Exception& excep){ cout<<excep.errorInfo; return -1; } cout<<"query successfully"<<endl; for(size_t i=0;i<dataSet.size();++i){ cout<<dataSet[i]["courseName"]<<endl; } //修改学号为201421031060的学生专业 MysqlHelper::RECORD_DATA recordChange; recordChange.insert(make_pair("major",make_pair(MysqlHelper::DB_STR,"软件工程"))); try{ res=mysqlHelper.updateRecord("student",recordChange,"where studentNo=/"201421031060/""); }catch(MysqlHelper_Exception& excep){ cout<<excep.errorInfo; return -1; } cout<<"res:"<<res<<" update successfully"<<endl; return 0;}

################################### @brief:make scripts# @date:2016.05.28# @author:lvlv###################################environment varVPATH+=.CC:=g++FLAGS=-g -Wall -std=c++11INC+=-I/usr/local/mysql/includeLIBDIR+=-L/usr/local/mysql/libCPPDIRS=.CPPS=$(shell for dir in ${CPPDIRS};do echo $${dir}/*.cpp;done)OBJDIR=objOBJS=$(patsubst %.cpp,${OBJDIR}/%.o,$(notdir ${CPPS}))TARGET:=mysqlDemo.out${TARGET}:${OBJS} ${CC} ${FLAGS} ${OBJS} -o $@ ${LIBDIR} -lmysqlclient${OBJDIR}/%.o:./%.cpp ${CC} ${FLAGS} ${INC} -o $@ -c $<.PHONY:cleanclean: rm -f ${TARGET} ${OBJDIR}/*