Linux下使用C/C++访问数据库——SQL Server篇

在Linux下连接MSSQL是一件很痛苦的事，因为微软同志没有提供任何接口给开发人员，大约他们认为要用MSSQL的，只可能是windows的操作系统。还好，MSSQL是从Sybase衍生出来的，有一些哥们做了一些Sybase的Linux下的连接库，这些连接库同时也能支持MSSQL，FreeTDS就是这样的一个东东。

这篇文章的受用读者，我想是那些希望在Linux或Unix下编写C或C++程序来连接MSSQL2000的兄弟们，因为我就是这样的。同时，那些写PHP的哥们也可以参考一下，当然如果你是用PHP的，你恐怕还要知道APACHE以及PHP脚本的安装，或者关于PHP自定义Module的开发，可以参考我以前写的一篇Blog（ PHP5自定义Module开发）。

下面开始我们的探索之旅：

一、相关软件

首先我们需要FreeTDS的安装包，可以在这个地址下载到： http://ibiblio.org/pub/Linux/ALPHA/freetds/stable/freetds-stable.tgz

现在的最新版是0.82

其次就是大家需要自己搭建C++的开发环境了。

二、软件安装、配置

# tar zxvf freetds-stable.tgz（解压）

# ./configure --prefix=/usr/local/freetds \（指定FreeTDS安装路径）
     --with-tdsver=8.0 --enable-msdblib （设置TDS版本，支持SQL Server 2000）

# make

# make install

将freetds的库文件所在路径配置到LD_LIBRARY_PATH参数中：
$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/freetds/lib/:
这么作的目的是为了避免加载FreeTds库文件加载不上的情况。

三、程序开发

不多说了，还是直接上代码：

/*    
* SyBaseManager.h    
*    
*    Created .: Feb 18, 2009    
*            Author: Steven Wee    
*/    

#ifndef SYBASEMANAGER_H_    
#define SYBASEMANAGER_H_    

#include "../Common/CheckStringTools.h"    

#include     
#include     
#include     
#include     
#include     
#include     
#include     

#include     
#include     

using namespace std;    

class SybaseManager    
{    
public:    
        SybaseManager(std::string hosts, std::string userName, std::string password, std::string dbName, unsigned int port);    
        ~SybaseManager();    
        /*    
         * Init SQL Server    
         * @param hosts:         Host IP address    
         * @param userName:        Login UserName    
         * @param password:        Login Password    
         * @param dbName:        Database Name    
         * @param port:                Host listen port number    
         */    
        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 > 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;    
        DBPROCESS *dbProcess;    
        vector< vector > resultList;    
        unsigned int DEFAULTPORT;    
        char * HOSTS;    
        char * USERNAME;    
        char * PASSWORD;    
        char * DBNAME;    
};    

#endif /* SYBASEMANAGER_H_ */

/*    
* SyBaseManager.cpp    
*    
*    Created .: Feb 18, 2009    
*            Author: Steven Wee    
*/    
#include "SybaseManager.h"    

SybaseManager::SybaseManager(std::string hosts, std::string userName, std::string password, std::string dbName, unsigned int port)    
{    
        IsConnected = false;    
        this ->setHosts(hosts);    
        this ->setUserName(userName);    
        this ->setPassword(password);    
        this ->setDBName(dbName);    
        this ->setPort(port);    
}    

SybaseManager::~SybaseManager()    
{    
        destroyConnection();    
}    

void SybaseManager::setDBName(string dbName)    
{    
        if ( dbName.empty() )    
        {    
                std::cout << "DBName is null! Used default value: master" << std::endl;    
                this ->DBNAME = new char[5];    
                strcpy(this ->DBNAME, "master");    
        }    
        else    
        {    
                this ->DBNAME = new char[dbName.length()];    
                strcpy(this ->DBNAME, dbName.c_str());    
        }    
}    

void SybaseManager::setHosts(string hosts)    
{    
        if ( hosts.empty() )    
        {    
                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 SybaseManager::setPassword(string password)    
{    
        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 SybaseManager::setPort(unsigned int port)    
{    
        if ( port )    
        {    
                std::cout << "Port number is null! Used default value: 0" << std::endl;    
                this ->DEFAULTPORT = 0;    
        }    
        else    
        {    
                this ->DEFAULTPORT = port;    
        }    
}    

void SybaseManager::setUserName(string userName)    
{    
        if ( userName.empty() )    
        {    
                std::cout << "UserName is null! Used default value: sa" << std::endl;    
                this ->USERNAME = new char[4];    
                strcpy(this ->USERNAME, "sa");    
        }    
        else    
        {    
                this ->USERNAME = new char[userName.length()];    
                strcpy(this ->USERNAME, userName.c_str());    
        }    
}    

void SybaseManager::initConnection()    
{    
        string Charset = "UTF-8";    
        dbinit();    
        LOGINREC *loginREC = dblogin();    
        DBSETLUSER(loginREC, this ->USERNAME);    
        DBSETLPWD(loginREC, this ->PASSWORD);    
        DBSETLCHARSET(loginREC, Charset.c_str());    
        dbProcess = dbopen(loginREC, this ->HOSTS);    
        if ( dbProcess == FAIL )    
        {    
                std::cout << "Connect to SQL Server failed!" << std::endl;    
        }    
        if ( dbuse( dbProcess, this ->DBNAME ) == FAIL )    
        {    
                std::cout << "Use table failed!" << std::endl;    
        }    
}    

bool SybaseManager::runSQLCommand( string sql )    
{    
        dbcmd(dbProcess, sql.c_str());    
        if ( dbsqlexec(dbProcess) == FAIL )    
        {    
                std::cout << "Query from database failed!" << std::endl;    
        }    
        DBINT result_code;    
        vector objectValue;    
        StringTools stringTools;    

        sql = stringTools.filterString(sql);    

        while ( (result_code = dbresults(dbProcess)) != NO_MORE_RESULTS )    
        {    
                struct Column    
                {    
                        char* colName;    
                        char* colBuffer;    
                        int colType, colSize, colStatus;    
                } *columns, *pCol;    
                int nColumns;    
                int rowNo;    
                if ( result_code == SUCCEED )    
                {    
                        nColumns = dbnumcols(dbProcess);    
                        if ( (columns = (Column*)calloc(nColumns, sizeof(struct Column))) == NULL )    
                        {    
                                std::cout << "Error at bind data" << std::endl;    
                                return false;    
                        }    
                        for ( pCol = columns; pCol - columns < nColumns; pCol++ )    
                        {    
                                int colNo = pCol - columns + 1;    
                                pCol ->colName = dbcolname(dbProcess, colNo);    
                                pCol ->colType = dbcoltype(dbProcess, colNo);    
                                pCol ->colSize = dbcollen(dbProcess, colNo);    
                                if ( SYBCHAR != pCol ->colType )    
                                {    
                                        pCol ->colSize = dbwillconvert(pCol ->colType, SYBCHAR);    
                                }    

                                if ( (pCol ->colBuffer = (char*)calloc(1, pCol ->colSize + 1)) == NULL )    
                                {    
                                        std::cout << "Check column buffer error!" << std::endl;    
                                        return false;    
                                }    

                                if ( dbbind(dbProcess, colNo, STRINGBIND, pCol ->colSize + 1, (BYTE*)pCol ->colBuffer) == FAIL )    
                                {    
                                        std::cout << "Running dbbind() error!" << std::endl;    
                                        return false;    
                                }    

                                if ( dbnullbind(dbProcess, colNo, &pCol ->colStatus) == FAIL )    
                                {    
                                        std::cout << "Running dbnullbind() error!" << std::endl;    
                                        return false;    
                                }    
                        }    

                        while ( (rowNo = dbnextrow(dbProcess)) != NO_MORE_ROWS )    
                        {    
                                objectValue.clear();    
                                switch ( rowNo )    
                                {    
                                case REG_ROW:    
                                        for ( pCol = columns; pCol - columns < nColumns; pCol++ )    
                                        {    
                                                const char* columnBuffer = pCol ->colStatus == -1 ? "NULL" : pCol ->colBuffer;    
                                                objectValue.push_back(stringTools.Trim(columnBuffer));        //        std::cout << columnBuffer << std::endl;    
                                        }    
                                        break;    
                                case BUF_FULL:    
                                        assert( rowNo != BUF_FULL );    
                                        break;    
                                case FAIL:    
                                        std::cout << "Get result error!" << std::endl;    
                                        break;    
                                default:    
                                        std::cout << "Get result ignore, row number:" << rowNo << std::endl;    
                                }    
                                this ->resultList.push_back(objectValue);    
                        }    
                        for ( pCol = columns; pCol - columns < nColumns; pCol++ )    
                        {    
                                free( pCol ->colBuffer );    
                        }    
                        free( columns );    
                        /*    
                        if ( DBCOUNT(dbProcess) > -1 )    
                        {    
                                std::cout << "Affected rows:" << DBCOUNT(dbProcess) << std::endl;    
                        }    
                        */    
                        if ( dbhasretstat(dbProcess) == TRUE )    
                        {    
                                std::cout << "Procedure returned " << dbhasretstat(dbProcess) << std::endl;    
                        }    
                }    
        }    
        return true;    
}    

void SybaseManager::destroyConnection()    
{    
        dbclose(dbProcess);    
}    

bool SybaseManager::getConnectionStatus()    
{    
        return IsConnected;    
}    

vector< vector > SybaseManager::getResult()    
{    
        return this ->resultList;    
}

 

四、修改建议

本人在以后的完善中，打算把runSQLCommand(char * sql)函数分解成两个或者三个函数，分别执行select和insert等语句。

在程序中，我并没有强制要求参数必须为const，可能会出现一些安全问题。

本文仅起抛砖引玉的作用，希望有高手可以指点我程序中的问题。

 

敬请期待下一篇文章：Linux下使用C/C++访问数据库——Oracle之OCI篇