c++ - 如何使用 libpqxx 获取 postgres sqlerrorcode？

Question

我想知道如何在插入等后获取 postgres sql 错误代码。？

Answer 1

这是来自文档的代码片段:

try
{
  // ...
}
catch (const pqxx::pqxx_exception &e)
{
  std::cerr << e.base().what() << std::endl;
  const pqxx::sql_error *s=dynamic_cast<const pqxx::sql_error*>(&e.base());
  if (s) std::cerr << "Query was: " << s->query() << std::endl;
}

一旦出现 sql_error，您就可以从中检索 sql 状态:

std::cerr  << "SQL STATE: " << s->sqlstate() << std::endl;

所以改变上面的代码sippet:

pqxx::connection dbConn("dbname=tester user=foo");
pqxx::result r;
try
{
  pqxx::work transx(dbConn);
  std::string query ("SELECT name FROM compamy");
  r = transx.exec(query);
  transx.commit();  // Not necessary for a SELECT, but good practice
}
catch (const pqxx::pqxx_exception &e)
{
  std::cerr << e.base().what() << std::endl;
  const pqxx::sql_error *s=dynamic_cast<const pqxx::sql_error*>(&e.base());
  if (s) {
    std::cerr << "SQL Error code: " << s->sqlstate() << std::endl;
  }
}

假设表名称是 company，而不是 compamy，则得到以下输出:

SQL Error code: 42P01

从 Postgresql error codes 查找该代码表:

42P01   undefined_table