PHP中的循环不起作用

Question

$qPhysician = mysql_query("SELECT * FROM physicians");
$num = mysql_num_rows($qPhysician);
$i=0;
while($i < $num)
{
    "<tr>";
    "<td>" . mysql_result($qPhysician,$i,"lastName") . "</td>";
    "<td>" . mysql_result($qPhysician,$i,"firstName") . "</td>";
    "</tr>";
    $i++;
}

我得到空白结果。

如果我回显$num，我会得到“19”，这是我的数据库中的行数。 如果我回显$rowPhysician['lastName'] 只是为了测试我是否获得记录，我会获得至少1 条姓氏记录。我不知道“while”是否有问题。请帮帮我。

Answer 1

您是否错过了打印字符串的回声？

while($i < $num) {
    echo "tr";
    echo "td" . mysql_result($qPhysician,$i,"lastName") . "/td";
    echo "td" . mysql_result($qPhysician,$i,"firstName") . "/td";
    echo "/tr";
    $i++;
}

Answer 2

从技术上讲，这不是答案，但以这种方式显示代码更容易：

// first, only take the records you need -- each record adds more time to
// query, so if you only need 2, only select 2.
$query = mysql_query("SELECT lastName, firstName FROM physicians");

// mysql_fetch_assoc returns an associative array of all of the columns
// mysql_fetch_row   returns a numerically indexed array.
// mysql_fetch_array returns an array with both numeric and string indexing.
// they will all return FALSE when there are no more results in the query.
while( $arr = mysql_fetch_assoc( $query ) )
{
    echo "<tr>";
    // Now, use array indexing.
    echo "<td>" . $arr[ "lastName" ] . "</td>";
    echo "<td>" . $arr[ "firstName" ] . "</td>";
    echo "</tr>";
}

mysql_result 实际上是一个更好的选择是非常罕见的情况——通常最好只在 PHP 中填充几个数组并使用数据库来完成。

Answer 3

无论如何，回显 HTML 是不好的做法。更正确的输出应该是这样的

...
while($i < $num) :?>
    <tr>
      <td><?php echo mysql_result($qPhysician,$i,"lastName"); ?></td>
      <td><?php echo mysql_result($qPhysician,$i,"firstName") ?></td>
    </tr>
<?php $i++; endwhile;
...

请注意，您也写错了关闭 HTML。