/*
 * call-seq:
 *    conn.query( sql )
 *
 * Sends SQL query request specified by _sql_ to the PostgreSQL.
 * Returns an Array as the resulting tuple on success.
 * On failure, it returns +nil+, and the error details can be obtained by #error.
 */
static VALUE
pgconn_query(obj, str)
  VALUE obj, str;
{
  return pgresult_result_with_clear(pgconn_exec(obj, str));
}