最近在学Ubuntu软件开发，需要嵌入式数据库，作为备忘录，也希望对初学者有所帮助
首先安装MySQL
sudo apt-get install mysql-server mysql-client
再安装G++依赖的mysql.h的依赖包，见另一篇博客：fatal error： mysql.h:没有那个文件或目录
sudo apt-get install libmysqlclient-dev
运行MySQL
mysql -u root -p
创建一个简单的数据库
mysql>create database test; mysql>use test; //切换到test数据库中 mysql> create table test(name varchar(255),num int(10) ); //创建一个叫test的表 mysql>show create table test; //显示刚才创建的表信息 mysql> select * from test; //查询test表中数据 mysql>quit用vim简单写一个test.cpp 的测试文件
#include <stdio.h> #include <mysql.h> int main(int argc,char *argv[]) { MYSQL conn; int res; mysql_init(&conn); if(mysql_real_connect(&conn,"localhost","root","8520","test",0,NULL,CLIENT_FOUND_ROWS)) //"root":数据库管理员 "":root密码 "test":数据库的名字 { printf("connect success!\n"); res=mysql_query(&conn,"insert into test values('user','123456')"); if(res) { printf("error\n"); } else { printf("OK\n"); } mysql_close(&conn); } else { printf("Database can not connect!!!!"); } return 0; }编译命令：注意`是跟波浪线在一起的那个符号 g++ test.cpp `mysql_config --cflags --libs` -o test运行test ./test就可以把这条数据存储进MySQL了
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接下来是多文件，多线程访问数据库。目前还有bug。。。数据库总报错，连接不上
/***************** main.cc ******************/ #include "MySQLManager.h" #include <iostream> #include <vector> using namespace std; int main() { MySQLManager *mysql = new MySQLManager("127.0.0.1", "root", "xufeiyang", "mytest", (unsigned int)3306); mysql->initConnection(); if(mysql->getConnectionStatus()) { if(mysql->runSQLCommand("select * from student")) { vector<vector<std::string> > result = mysql->getResult(); for(auto & vec : result) { for(auto &str : vec) {cout << str.c_str() << " ";} cout << endl; } } else cout << "执行失败" << endl; } else cout << "连接未建立" << endl; return 0; } /* * MySQLManager.h */ #ifndef MYSQLMANAGER_H_ #define MYSQLMANAGER_H_ #include <mysql.h> #include <string> #include <iostream> #include <vector> #include <string.h> using namespace std; class MySQLManager { public: MySQLManager(std::string hosts, std::string userName, std::string password, std::string dbName, unsigned int port); ~MySQLManager(); void initConnection(); bool runSQLCommand(std::string sql); unsigned int insert(std::string sql); 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.cc ***************************************/ #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 <= 0 ) { 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) ) {// 连接到服务器连接到服务器 cout << "HHHHHHHHHHHHH"<<endl; std::cout << "Error connection to database: \n" << mysql_error(&mySQLClient) << std::endl; } IsConnected = true;// 修改连接标识 } bool MySQLManager::runSQLCommand(string sql) { if (!IsConnected ) { 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; i = mysql_real_query(&mySQLClient,sql.c_str(),(unsigned int)strlen(sql.c_str()));// 执行查询 if ( i < 0 ) { std::cout << "Error query from database: \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; } unsigned int MySQLManager::insert(std::string sql) { if(!IsConnected) { cout << "" << endl; return -1; } if(sql.empty()){ cout << "sql is null " << endl; return -1; } int rows = -1; int res = mysql_query(&mySQLClient, sql.c_str()); if(res >= 0){ // 返回受影响的行数 rows = mysql_affected_rows(&mySQLClient); cout << "Inserted "<< rows << " rows\n"; return rows; } else { cout << "Insert error " << mysql_errno(&mySQLClient) << "," << mysql_error(&mySQLClient) << endl; return -1; } } vector< vector<string> > MySQLManager::getResult() { return resultList; } void MySQLManager::destroyConnection() { mysql_close(&mySQLClient); this ->IsConnected = false; } bool MySQLManager::getConnectionStatus() { return IsConnected; } 编译 g++ main.cc MySQLManager.cc -o main -std=c++11 -I/usr/include/mysql -L/usr/lib/mysql -lmysqlclient