C++用mysql自带的头文件连接数据库

#include 
#include 
#include
#include
#include
using namespace std;
MYSQL *conn;
 MYSQL_RES *res;
 MYSQL_ROW row;
 
class people
{
public:
  char name[20];
  int pid;
  int type;
  char phone[30];
public:
  people(int a){};
  people(){
    setall();
  };
  ~people(){};
public:
  void setall();
 
};
 
void people::setall()
{
  cout<<"请输入该用户的编号"<>pid;
  cout<<"请输入该用户的名字"<>name;
  cout<<"请输入该用户的类型"<>type;
  cout<<"请输入该用户的联系方式"<>phone;
 
}
void save()
{
  char sql[1000];
  people a;
  sprintf(sql,"insert into student values(%d,'%s',%d,'%s')",a.pid,a.name,a.type,a.phone);
  if(mysql_query(conn, sql))
    {
      printf("添加失败: (%s)\n",mysql_error(conn));
      return;
    }
    else
    {
      printf("添加成功!\n");
      return;
    }
  return;
}
void update(){
  char sql[1000];
  people a(1);
  cout<<"请输入你要更改的用户的编号:";
  cin >> a.pid;
  cout<<"请输入你要此编号用户的姓名：";
  cin >> a.name;
  cout <<"请输入你要更改的用户的类型：";
  cin >> a.type;
  cout <<"请输入你要更改的用户的电话：";
  cin >> a.phone;
  sprintf(sql,"update student set name = '%s',usetype=%d,phOne='%s' where pid = %d",a.name,a.type,a.phone,a.pid);
    if(mysql_query(conn, sql))
      {
        printf("更改失败： (%s)\n",mysql_error(conn));
        return;
      }
      else
      {
        printf("更改成功!\n");
        return;
      }
    return;
}
void del()
{
  char sql[1000];
  int pid;
  cout<<"请输入你要删除的人的编号"<>pid;
  sprintf(sql,"delete from student where pid = %d",pid);
  if(mysql_query(conn, sql))
    {
      printf("删除 失败(%s)\n",mysql_error(conn));
      return;
    }
    else
    {
      printf("删除成功!\n");
      return;
    }
  return;
}
void menu()
{
  cout<<"1.用户录入"<>s;
    if(s==2){show();}
    if(s==1){save();}
    if(s==3){update();}
    if(s==4){del();}
    if(s==5){mysql_close(conn);return 0;}
    cout<<"按任意键继续.."<