php - MYSQL 当 mysql_fetch_assoc =1 时不返回

Question

我有以下 PHP，它从 MySQL 查询创建一些 JSON。当有多个元素时，即 mysql_fetch_assoc > 1 时，这种方法可以正常工作，但如果它 = 1，则没有任何作用和调试，while 循环内的任何 echo 语句都不会被调用!

这是怎么回事？

$byFlight = mysql_query($query_byFlight, $pfArchiveDB) or die(mysql_error());
$row_byFlight = mysql_fetch_assoc($byFlight);
//$totalRows_byFlight = mysql_num_rows($byFlight);
//echo ($query_byFlight);
$flights = array();
if(mysql_num_rows($byFlight)) {
    while($flight = mysql_fetch_assoc($byFlight)) {
        $flights[] = array('flight'=>$flight);
    }
}
header('Content-type: application/json');
echo json_encode(array('flights'=>$flights));

Answer 1

您正在执行两次提取，这可能会消耗您的第一行。这段代码可以正常工作:

$byFlight = mysql_query($query_byFlight, $pfArchiveDB) or die(mysql_error());

 //$row_byFlight = mysql_fetch_assoc($byFlight); // <---- COMMENTED THIS FETCH

//$totalRows_byFlight = mysql_num_rows($byFlight);
//echo ($query_byFlight);
$flights = array();
if(mysql_num_rows($byFlight)) {
    while($flight = mysql_fetch_assoc($byFlight)) {
        $flights[] = array('flight'=>$flight);
    }
}
header('Content-type: application/json');
echo json_encode(array('flights'=>$flights));