working libpqxx example

libpqxx_test.cpp

#include <iostream>
#include <chrono>
#include <pqxx/pqxx>

int main(int, char *argv[])
{
  pqxx::connection c("dbname=arete user=postgres password=postgres");

  {
    pqxx::work txn(c);

    pqxx::result r = txn.exec(
      "create table if not exists employee(id serial primary key, name text, salary integer)");

    txn.commit();
  }
  
  c.prepare("insert_employee", "insert into employee(name, salary) values($1, $2)");

  auto start = std::chrono::high_resolution_clock::now();

  pqxx::work txn(c);

  txn.exec_prepared0("insert_employee", "Warren", 12345);
    
  pqxx::result r = txn.exec(
    "SELECT id "
    "FROM Employee "
    "WHERE name =" + txn.quote("Warren") + " order by id desc limit 1");

  if (r.size() != 1)
  {
    std::cerr
      << "Expected 1 employee with name 'Warren', "
      << "but found " << r.size() << std::endl;
    return 1;
  }

  int employee_id = r[0][0].as<int>();
  std::cout << "Updating employee #" << employee_id << std::endl;

  txn.exec(
    "UPDATE EMPLOYEE "
    "SET salary = salary + 1 "
    "WHERE id = " + txn.quote(employee_id));

  txn.commit();

  auto end = std::chrono::high_resolution_clock::now();

  std::chrono::duration<double> elapsed_seconds = std::chrono::duration_cast<std::chrono::duration<double>>(end - start);

  std::cout << "Done in " << elapsed_seconds.count() << 'ms\n';

  std::cin.get();
}