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官方文檔

機(jī)器配置

機(jī)器環(huán)境：mac 10.14
mysql版本：8.0.4-rc，自行編譯，編譯步驟
mysql 存放路徑：/Users/shiyibo/LNMP/mysql
IDE: CLion

目錄劃分：

| - main.cpp
| - myDb.h
| - MyDb.cpp

代碼

/**
 * file MyDb.h
 *
 * Created by shiyibo on 2018/12/21.
 */

#ifndef DB_MYDB_H
#define DB_MYDB_H

#include <string>
#include "/Users/shiyibo/LNMP/mysql/include/mysql.h"

using namespace std;

class MyDb {

public:
    MyDb();
    ~MyDb();

    /**
     * 連接mysql
     *
     * @param host
     * @param user
     * @param pwd
     * @param db_name
     * @param port
     * @return
     */
    bool initDB(string host, string user,string pwd,string db_name, int port);

    /**
     * 執(zhí)行sql語(yǔ)句
     *
     * @param sql
     * @return
     */
    bool exeSQL(string sql);

private:
    /**
     * 連接mysql句柄指針
     */
    MYSQL *mysql;

    /**
     * 指向查詢結(jié)果的指針
     */
    MYSQL_RES *result;

    /**
     * 按行返回的查詢信息
     */
    MYSQL_ROW row;
};
#endif //DB_MYDB_H

/**
 * file MyDb.cpp
 * Created by shiyibo on 2018/12/21.
 */

#include <iostream>
#include <string>
#include "MyDb.h"

using namespace std;

/**
 * 初始化數(shù)據(jù)庫(kù)連接變量
 */
MyDb::MyDb()
{
    mysql = mysql_init(NULL);

    if(!mysql) {
        cout<<"Error:"<<mysql_error(mysql);
        exit(1);
    }
}

/**
 * 釋放資源
 */
MyDb::~MyDb()
{
    if(mysql) {
        mysql_close(mysql);
    }
}

/**
 *
 * @param host
 * @param user
 * @param passwd
 * @param db_name
 * @oaram port
 * @return
 */
bool MyDb::initDB(std::string host, std::string user, std::string passwd, std::string db_name, int port = 3306)
{
    mysql = mysql_real_connect(mysql, host.c_str(), user.c_str(), passwd.c_str(), db_name.c_str(), port, NULL, 0);
    if(!mysql) {
        cout << "Error: " << mysql_error(mysql);
        exit(1);
    }

    return true;
}

/**
 *  執(zhí)行sql 語(yǔ)句
 * @param sql
 * @return
 */
bool MyDb::exeSQL(std::string sql)
{
    //mysql_query()執(zhí)行成功返回0,執(zhí)行失敗返回非0值。
    if (mysql_query(mysql,sql.c_str())) {
        cout<<"Query Error: "<<mysql_error(mysql);
        return false;
    }

    result = mysql_store_result(mysql);

    if (result) {
        //獲取結(jié)果集中總共的字段數(shù)，即列數(shù)
        int               num_fields = mysql_num_fields(result);
        unsigned long long  num_rows = mysql_num_rows(result);

        for(unsigned long long i = 0; i < num_rows; i++) {
            row = mysql_fetch_row(result);
            if(!row) {
                break;
            }

            for(int j=0;j<num_fields;j++) {
                cout<<row[j]<<"\t\t";
            }
            cout<<endl;
        }
    } else {
        //代表執(zhí)行的是update,insert,delete類的非查詢語(yǔ)句
        if (mysql_field_count(mysql) == 0) {
            // 返回update,insert,delete影響的行數(shù)
            unsigned long long num_rows = mysql_affected_rows(mysql);

            return num_rows;
        } else {
            cout << "Get result error: " << mysql_error(mysql);
            return false;
        }
    }

    return true;
}

#include <iostream>
#include "MyDb.h"

int main() {
    // std::cout << "Hello, World!" << std::endl;

    MyDb db;

    string host = "127.0.0.1";
    string user = "root";
    string passwd = "password";
    string dbName = "test";
    int port = 3307;

    cout<<"start\n";

    //連接數(shù)據(jù)庫(kù)
    bool conn = db.initDB(host, user, passwd, dbName, port);

    if (!conn) {
        cout<<"connect fails\n";
    }

    cout<<"ok" <<endl;

    //將用戶信息添加到數(shù)據(jù)庫(kù)
    string sql = "INSERT account values(1, 'fengxin');";
    db.exeSQL(sql);

    sql = "INSERT account values(2, 'axin');";
    db.exeSQL(sql);

    //將所有用戶信息讀出，并輸出。
    sql = "SELECT * from account;";
    db.exeSQL(sql);

    return 0;
}

編譯

g++  main.cpp MyDB.cpp -o main  `mysql_config --cflags --libs`

運(yùn)行

image.png

數(shù)據(jù)表

CREATE TABLE `account` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(25) NOT NULL DEFAULT '',
  PRIMARY KEY (`id`)
)

image.png

問(wèn)題

• 運(yùn)行時(shí)遇到如下報(bào)錯(cuò)

./main
dyld: Library not loaded: @rpath/libmysqlclient.21.dylib
  Referenced from: /Users/shiyibo/CLionProjects/db/./main
  Reason: image not found
Abort trap: 6

解決方案：

• 方案1，來(lái)源

 1、關(guān)閉csrutil
 2、找到mysql安裝路徑，建立軟連接

sudo ln -s /usr/local/mysql/lib/libmysqlclient.21.dylib /usr/lib/libmysqlclient.21.dylib

效果: 原意是，建立一個(gè)從/usr/lib/libmysqlclient.21.dylib到/usr/local/mysql/lib/libmysqlclient.21.dylib的軟連；
環(huán)境中編譯的地址為 /Users/shiyibo/LNMP/mysql，默認(rèn)的按照路徑/usr/local/mysql/lib/libmysqlclient.21.dylib中沒(méi)有這個(gè)目錄；
換成了
sudo ln -s /Users/shiyibo/LNMP/mysql/lib/libmysqlclient.21.dylib /usr/lib/libmysqlclient21.dylib，重試，不管用；

• 方案2，來(lái)源

sudo ln -s /usr/local/mysql/lib/libmysqlclient.18.dylib/usr/lib/libmysqlclient.18.dylib     
或
export DYLD_LIBRARY_PATH="$DYLD_LIBRARY_PATH:/usr/local/mysql/lib/"

使用第二種方案，可以成功編譯，當(dāng)然，路徑也得換為/Users/shiyibo/LNMP/mysql/lib

最后

好多年不寫C系列，代碼丑陋，生疏，敬請(qǐng)諒解！

參考

Linux下C++連MySQL數(shù)據(jù)庫(kù)

linux下c++連接mysql數(shù)據(jù)庫(kù)