Linux下MySQL c++ connector示例

最近在學習數據庫的內容，起先是在windows下用mysql c++ connector進行編程，之所以選用c++而不是c的api，主要是考慮到c++ connector是按照JDBC的api進行實現的，使用比較方便。廢話不多說，直接上代碼。代碼主要是對常用操作的測試與封裝，包括DDL、DQL、DML，以及文本、圖像的讀寫方法

/*
 * SQLWork.cpp
 *
 *  Created on: Dec 29, 2016
 *      Author: tla001
 */

#include "SQLWork.h"

SQLWork::SQLWork(string url,string user,string passwd) {
    // TODO Auto-generated constructor stub
    turl=url;
    tuser=user;
    tpasswd=passwd;
}
SQLWork::~SQLWork() {
    // TODO Auto-generated destructor stub
    if(res)
        delete res;
    if(stmt)
        delete stmt;
    if(con)
        delete con;
}

int SQLWork::doConnect(){
    try{
        dirver = get_driver_instance();  //連接數據庫
        con = dirver->connect(turl, tuser, tpasswd);
        con->setClientOption("characterSetResults", "utf8");
    }catch(SQLException &e){
        cout << "ERROR: " << e.what();
        cout << " (MySQL error code: " << e.getErrorCode();
        cout << ", SQLState: " << e.getSQLState() << ")" << endl;

        if (e.getErrorCode() == 1047) {
            /*
            Error: 1047 SQLSTATE: 08S01 (ER_UNKNOWN_COM_ERROR)
            Message: Unknown command
            */
            cout << "\nYour server does not seem to support Prepared Statements at all. ";
            cout << "Perhaps MYSQL < 4.1?" << endl;
        }

        return EXIT_FAILURE;
    } catch (runtime_error &e) {
        cout << "ERROR: " << e.what() << endl;

        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}
int SQLWork::changeCharacter(string chars){
    try{
        con->setClientOption("characterSetResults", chars);
    }catch(SQLException &e){
        cout << "ERROR: " << e.what();
        cout << " (MySQL error code: " << e.getErrorCode();
        cout << ", SQLState: " << e.getSQLState() << ")" << endl;

        if (e.getErrorCode() == 1047) {
            /*
            Error: 1047 SQLSTATE: 08S01 (ER_UNKNOWN_COM_ERROR)
            Message: Unknown command
            */
            cout << "\nYour server does not seem to support Prepared Statements at all. ";
            cout << "Perhaps MYSQL < 4.1?" << endl;
        }

        return EXIT_FAILURE;
    } catch (runtime_error &e) {
        cout << "ERROR: " << e.what() << endl;

        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}
int SQLWork::chooseDatabase(string db){
    try{
        con->setSchema(db);
        stmt = con->createStatement();  //從表中獲取所有信息
    }catch(SQLException &e){
        cout << "ERROR: " << e.what();
        cout << " (MySQL error code: " << e.getErrorCode();
        cout << ", SQLState: " << e.getSQLState() << ")" << endl;

        if (e.getErrorCode() == 1047) {
            /*
            Error: 1047 SQLSTATE: 08S01 (ER_UNKNOWN_COM_ERROR)
            Message: Unknown command
            */
            cout << "\nYour server does not seem to support Prepared Statements at all. ";
            cout << "Perhaps MYSQL < 4.1?" << endl;
        }

        return EXIT_FAILURE;
    } catch (runtime_error &e) {
        cout << "ERROR: " << e.what() << endl;

        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}

int SQLWork::doWork(){
    try{
        /*
         * 執行具體工作
         */
        //buildTest();
        //operateTable();
        //operateData();
        //operateDataPre();
        //queryData();
        queryDataPre();

    }catch(SQLException &e){
        cout << "ERROR: " << e.what();
        cout << " (MySQL error code: " << e.getErrorCode();
        cout << ", SQLState: " << e.getSQLState() << ")" << endl;

        if (e.getErrorCode() == 1047) {
            /*
            Error: 1047 SQLSTATE: 08S01 (ER_UNKNOWN_COM_ERROR)
            Message: Unknown command
            */
            cout << "\nYour server does not seem to support Prepared Statements at all. ";
            cout << "Perhaps MYSQL < 4.1?" << endl;
        }

        return EXIT_FAILURE;
    } catch (runtime_error &e) {
        cout << "ERROR: " << e.what() << endl;

        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}

void SQLWork::buildTest(){
    res = stmt->executeQuery("SELECT * from student");  //循環遍歷
    while (res->next())  {   //輸出，id，name，age字段的信息
        cout << res->getInt("id")
            << " | " << res->getString(2)
            << " | " << res->getInt("tage")
            << " | " << res->getString("thome")
            << endl;
    }  //清理
}

/*
 * 執行DDL語句Data Definition Language 數據定義語言
 */
void SQLWork::operateTable(){
    //string sqlOp="create table contact(id int primary key auto_increment,name varchar(20),gender varchar(2))";
    //string sqlOp="drop table contact";
    //string sqlOp="ALTER TABLE contact ADD  home VARCHAR(30)";
    //string sqlOp="ALTER TABLE contact drop  home";
    //string sqlOp="ALTER TABLE contact MODIFY gender VARCHAR(4)";
    //string sqlOp="ALTER TABLE contact CHANGE thome home VARCHAR(20);";
    string sqlOp="CREATE TABLE longtest(id INT PRIMARY KEY AUTO_INCREMENT,content LONGTEXT,img LONGBLOB)";

    int count=stmt->executeUpdate(sqlOp);
    cout<<"count "<<count<<endl;
}

/*
 * DML（Data Manipulation Language 數據操控語言）
 */
void SQLWork::operateData(){
    //string sqlOp="INSERT INTO contact VALUES(2,'李','男','shenyang')";
    //string sqlOp="insert contact(name,gender) values('王二丫','女')";
    //string sqlOp="DELETE FROM contact WHERE id>2 and id<5";
    string sqlOp="UPDATE contact SET name='韓' WHERE id=2;";
    //string sqlOp="";
    //string sqlOp="";

    int count=stmt->executeUpdate(sqlOp);
    cout<<"count "<<count<<endl;
}
void SQLWork::operateDataPre(){
    //預編譯插入
//    string sqlOp="insert contact(name,gender) values(?,?)";
//    pstmt=con->prepareStatement(sqlOp);
//    pstmt->setString(1,"李四");
//    pstmt->setString(2,"男");

    //預編譯修改
//    string sqlOp="UPDATE contact SET name=? WHERE id=?";
//    pstmt=con->prepareStatement(sqlOp);
//    pstmt->setString(1,"王二");
//    pstmt->setInt(2,1);

    //預編譯刪除
//    string sqlOp="DELETE FROM contact WHERE id>?";
//    pstmt=con->prepareStatement(sqlOp);
//    pstmt->setInt(1,4);

//    int count=pstmt->executeUpdate();
//    cout<<"count "<<count<<endl;


/***********************文本數據*****************************************/
    //保存大文本數據（longtext）
//    string sqlOp="insert longtest(content) values(?)";
//    pstmt=con->prepareStatement(sqlOp);
//    ifstream file;
//    file.open("./file.txt");
//    if(!file){
//        cout<<"open failed"<<endl;
//        exit(-1);
//    }
//    pstmt->setBlob(1,&file);
//
//    int count=pstmt->executeUpdate();
//    cout<<"count "<<count<<endl;
//    file.close();

/***********************二進制數據*****************************************/
    //保存二進制數據（longblob）
    string sqlOp="insert longtest(img) values(?)";
    pstmt=con->prepareStatement(sqlOp);
    ifstream file;
    file.open("./test.png",ios::binary);
    if(!file){
        cout<<"open failed"<<endl;
        exit(-1);
    }
    pstmt->setBlob(1,&file);

    int count=pstmt->executeUpdate();
    cout<<"count "<<count<<endl;
    file.close();
}
/*
 * 數據查詢語句DQL
 */
void SQLWork::queryData(){
    string sqlOp="SELECT * FROM contact";
    //string sqlOp="";
    //string sqlOp="";

    res = stmt->executeQuery(sqlOp);  //循環遍歷
        while (res->next())  {
            int id=res->getInt("id");
            string name=res->getString("name");
            string gender=res->getString("gender");
            string home=res->getString("home");
            cout<<"id: "<<id<<"\t| name: "<<name<<"\t| gender: "<<gender<<"\t| home: "<<home<<endl;
        }
}

void SQLWork::queryDataPre(){
    //預編譯查詢
//    string sqlOp="SELECT * FROM contact";
//    //string sqlOp="";
//    //string sqlOp="";
//    pstmt=con->prepareStatement(sqlOp);
//    res = pstmt->executeQuery();
//        while (res->next())  {
//            int id=res->getInt("id");
//            string name=res->getString("name");
//            string gender=res->getString("gender");
//            string home=res->getString("home");
//            cout<<"id: "<<id<<"\t| name: "<<name<<"\t| gender: "<<gender<<"\t| home: "<<home<<endl;
//        }

/***********************文本數據*****************************************/
    //查詢大文件數據
//    string sqlOp="SELECT * FROM longtest";
//
//    pstmt=con->prepareStatement(sqlOp);
//    res = pstmt->executeQuery();
//    while (res->next())  {
//        string content=res->getString("content");
//        cout<<content<<endl;
//    }
/***********************二進制數據*****************************************/
    //查詢二進制數據
    string sqlOp="SELECT * FROM longtest";

    pstmt=con->prepareStatement(sqlOp);
    res = pstmt->executeQuery();
    int i=0;
    while (res->next())  {
        i++;
        ostringstream iname;
        iname <<"img"<<i<<".png";
        istream *is=res->getBlob("img");
        if(is->peek()>0){
            ofstream file(iname.str().c_str(),ios::binary);
            char data[1024];
            while(is->read(data,1024)){
                file.write(data,sizeof(data));
            }
            file.write(data,sizeof(data));
            file.close();
        }
    }
}

 

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