Question

如果变量为空，我正试图弄清楚如何跳过从MySQL表中打印一行。例如，我有一张充满信息的表格。我有一个while循环，回应结果。如果变量为空，如何跳过条目？

例如，如果'tweet1'在行中为空，我可以取消回声吗？

mysql_connect ($DBsever, $DBusername, $DBpass) or die ('I cannot connect to the database becasue: '.mysql_error());
mysql_select_db ("$DBname");

$query = mysql_query("SELECT * FROM $DBtable ORDER BY time");

while ($row = mysql_fetch_array($query)) {
    echo "<br /><strong>".$row['time']." ".$row['headline']."</strong><br/>".$row['description']."<br />".$row['story1']." <a href=".$row['link1']." target='_blank'>".$row['link1']."</a> ".$row['tweet1']."<br />";}

Answer 1

您可以使用continue控制结构跳过迭代。请阅读docs

示例：

if(!$row['tweet']) {
  continue;
}

Answer 2

if (empty($row['tweet'])) {
    continue;
}

Answer 3

你也可能无法返回tweet1中没有信息的行，这会使php检查tweet1中的数据变得不必要。

$query = mysql_query("SELECT * FROM $DBtable WHERE tweet1 IS NOT NULL ORDER BY time");

Answer 4

尝试：

while ($row = mysql_fetch_array($query)) {
if ($row['tweet1']) 
    echo "<br /><strong>".$row['time']." ".$row['headline']."</strong><br/>".$row['description']."<br />".$row['story1']." <a href=".$row['link1']." target='_blank'>".$row['link1']."</a> ".$row['tweet1']."<br />";
}

Answer 5

while ($row = mysql_fetch_array($query)) {
  if (!empty($row['tweet1'])    {
    echo "<br /><strong>".$row['time']." ".$row['headline']."</strong><br/>".$row['description']."<br />".$row['story1']." <a href=".$row['link1']." target='_blank'>".$row['link1']."</a> ".$row['tweet1']."<br />";
  }
}

如果变量为空，如何跳过while循环中的项？

5 个答案: