收藏:MySQL 5 C API 访问数据库例子程序

/*****************************************************************
以下是研究 mysql 5.0 得出的结果,描述并使用标准 c++演示了使用 MySQL
 C API 函数 简单操作数据库的流程;
 例子程序在 VC6 + windows 2000 上调试通过
*****************************************************************/
#include <windows.h> 
#include <iostream>
#include <mysql.h> //文件位于 MySQL 提供的 C API 目录(include)中
using namespace std;

// linux 等系统中请加入 -lmysql -I/usr/local/mysql/inlucde
#pragma comment( lib, "libmysql.lib")

class CMysqlConnect
{
private:
 //一个连接
 MYSQL *m_connmysql;
 std::string m_err;
protected:
 //
public:
 CMysqlConnect(const std::string &host,
            const std::string &user,
            const std::string &password,
      const std::string &dbname,
      unsigned int port);
 ~CMysqlConnect();
 //bool 
 //得到连接
 MYSQL * GetConnect();

 //得到错误消息
 const std::string What();
};

CMysqlConnect::CMysqlConnect(const std::string &host,
            const std::string &user,
            const std::string &password,
      const std::string &dbname,
      unsigned int port = MYSQL_PORT):m_connmysql(NULL)
{
 //初始化数据结构
 if((m_connmysql = mysql_init(m_connmysql)) == NULL)
 {
  return;
 }

 if(NULL == mysql_real_connect(m_connmysql,host.c_str(),
  user.c_str(),password.c_str(),dbname.c_str(),port,NULL,0))
 {
  m_err = mysql_error(m_connmysql);
  return ;
 }
}


CMysqlConnect::~CMysqlConnect()
{
 if(m_connmysql)
 {
  mysql_close(m_connmysql);
  m_connmysql = NULL;
 }
}


//得到连接
MYSQL * CMysqlConnect::GetConnect()
{
 if(m_connmysql == NULL)
 {
  //throw std::logic_error("db not connect");
 }

 //还需要判断是否能自动重新连接

 return m_connmysql;
}

 //得到错误消息
const std::string CMysqlConnect::What()
{
 return m_err;
}

/*****************************************************************/
///name       : main
//function    : 主测试函数
//access      : public
//para        : 
//         1. : int argc
//            : 系统参数个数
//         2. : char * argv[]
//            : 参数数值
//return      : 返回给 startup 函数的退出参数
//author      : hzh
//date        : 2006-06-24
/*****************************************************************/
int main( int argc, char * argv[] ) 
{   
 CMysqlConnect *myconn = NULL;  
 
 //连接数据库
 if(argc == 1)
 {
  myconn = new CMysqlConnect("127.0.0.1","root","mysql5",
   "test",MYSQL_PORT);
  if(myconn == NULL)
  {
   std::cout<<"allocate memory exception"<<endl;
   return -1;
  }
  if(myconn->GetConnect() == NULL)
  {
   std::cout<<"connect database fail"<<
    endl<<myconn->What().c_str()<<endl;
   return -1;
  }
 }else if(argc == 6)
 {
  myconn = new CMysqlConnect(argv[1],argv[2],argv[3],argv[4],atoi(argv[5]));
  if(myconn == NULL)
  {
   std::cout<<"allocate memory exception"<<endl;
   return -1;
  }
  if(NULL == myconn->GetConnect())
  {
   std::cout<<"connect database fail"<<endl<<
    myconn->What().c_str()<<endl;
   return -1;
  }
 }
 else
 {
  std::cout<<"run parameter error"<<endl;
  return -1;
 }

 MYSQL *mydata = myconn->GetConnect();

 //先删除数据表
 std::string s_sql = "drop table hzhtest";
 if(mysql_query(mydata,s_sql.c_str()) != 0)
 {
  //删除表失败
  std::cout<<"drop table fail"<<endl<<mysql_error(mydata)<<endl;
 }
 else
 {
  std::cout<<"drop table success"<<endl;
 }

 //创建数据表,字段 myid 设置了自增列属性
 s_sql = "create table hzhtest(";
 s_sql += "myid integer not null auto_increment,";
 s_sql += "mytime datetime null,myname varchar(30),";
 s_sql += " primary key(myid))";
 if(mysql_query(mydata,s_sql.c_str()) != 0)
 {
  //创建表失败
  std::cout<<"create table fail"<<endl;
  return -1;
 }
 else
 {
  std::cout<<"create table success"<<endl;
  std::cout<<s_sql.c_str()<<endl;
 }

 //向表中插入数据
 for(int k = 1; k < 30; ++k)
 {
  s_sql = "insert into hzhtest(mytime,myname) values";
  s_sql += "('2006-06-";
  char buff[20];
  memset(buff,0,sizeof(buff));
  itoa(k,buff,10);
  s_sql += buff;
  
  s_sql += " ";

  int i = k % 3;
  memset(buff,0,sizeof(buff));
  itoa(i,buff,10);
  s_sql += buff;
  s_sql += ":01:01'";

  if(i == 0)
  {
   s_sql += ",NULL";
  }
  else
  {
   s_sql += ",'中文显示测试";
   s_sql += buff;
   s_sql += "'";
  }
  s_sql += ")";

  if(mysql_query(mydata,s_sql.c_str()) != 0)
  {
   //执行SQL语句出错 
   std::cout<<"execute insert syntax fail"<<endl;
   return -1;
  } 
 }
 std::cout<<"insert data success"<<endl;

 //查询数据并显示
 s_sql = "select myid,mytime,myname from hzhtest";
 if(mysql_query(mydata,s_sql.c_str()) != 0)
 {
  //执行SQL语句出错 
  return -1;
 }  
 
 MYSQL_RES *result = mysql_store_result(mydata); 

 //取得查询结果 
 int rowcount = mysql_num_rows(result); 
 //取得有效记录数 
 std::cout<<"exec sql: "<<s_sql.c_str()<<
  ",row count: "<<rowcount<<endl;

 MYSQL_FIELD *fields = NULL; 
 //取得各字段名 
 for(int i = 0; fields = mysql_fetch_field(result);++i)
 {
  std::cout<<fields->name<<"\t\t";
 }
 std::cout<<endl;
   
 //依次读取各条记录 
 MYSQL_ROW currrow = NULL;
 while((currrow = mysql_fetch_row(result)) != NULL)
 {
  //读行的记录
  for(int i = 0; i < mysql_num_fields(result); ++i)
  {
   std::cout<<(currrow[i] ? currrow[i] : "NULL")<<"\t";
  }
  std::cout<<endl;
 }
 mysql_free_result(result) ; 

 system("pause");
 return 1;
}





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