我有这个代码在不同的脚本中工作。我正在做一些愚蠢的事情，但我看不到它。
<div>
<a href="view_accessory.php?id=<?php echo ++$pageno;?>"><div id='button'>Next</div> </a>
<a href="edit_acces_form.php?id=<?php echo $pageno; ?>"><div id='button'>Edit</div> </a>
<a href="view_accessory.php?id=<?php echo --$pageno;?>"><div id='button'>Previous</div> </a>
</div>
第一行有效，第二行有效，但第三行无效。如果我改变周围的线条，它们会单独工作 - 但不能一起工作。
这是整个代码 - 无论位置如何，编辑都有效。位于第二位的数学操作数将不起作用。
<!DOCTYPE html>
<html lang="en-US">
<head>
<title>View Accessory Data</title>
<link href="styles/main.css" type="text/css" rel="stylesheet">
</head>
<body>
<div align=center id="wrapper">
<div align="center" id="pagewrap">
<header>
<h1> View Accessory Data </h1>
</header>
<?php
require 'zxcvbn/db.inc.php';//database connection
if (!$pageno = \filter_input(INPUT_GET, "id", \FILTER_VALIDATE_INT)){
$pageno = 1;
} else {
$pageno = (int) $pageno;
}
echo "first pageno = ".$pageno;
$result0 = \mysqli_query($con, "SELECT COUNT(*) FROM accessory");
$numrows = \mysqli_fetch_row($result0);
$lastpage = ($numrows[0]);
$pageno = (int)$pageno;
if ($pageno > $lastpage) {
$pageno = 1;
// starts at the beginning
} // if
if ($pageno < 1) {
$pageno = $lastpage;
// goes to last record
} // if
//$pageno = $pageno-1;
?>
<div>
<a href="view_accessory.php?id=<?php echo ++$pageno;?>"><div id='button'>Next</div> </a>
<a href="edit_acces_form.php?id=<?php echo $pageno; ?>"><div id='button'>Edit</div> </a>
<a href="view_accessory.php?id=<?php echo --$pageno;?>"><div
id='button'>Previous</div> </a>
</div>
<?php
$result = \mysqli_query($con, "SELECT * FROM accessory where rec_number='$pageno'");
$row = \mysqli_fetch_row($result);
echo "<table bgcolor='white' ><tr><td>Name :</td><td>".htmlspecialchars($row[1])."
</td>
</tr>";
$sql="SELECT rec_number, name FROM tank WHERE rec_number=$row[2]";
$result2 = \mysqli_query($con, $sql);
$row2 = \mysqli_fetch_row($result2);
echo "<tr><td>Tank:</td><td>".\htmlspecialchars($row2[1])."</td></tr>";
echo "<tr><td>In Service Date:</td><td>".htmlspecialchars($row[3])."</td></tr>";
echo "<tr><td>Type :</td><td>".htmlspecialchars($row[4])."</td></tr>";
echo "<tr><td>Notes :</td><td>".htmlspecialchars($row[5])."</td></tr>";
echo "<tr><td>Picture :</td><td><img src=".$row[6]." width='50%'</td></tr>";
echo "</table bgcolor='#ecf2f8'>";
// Free result set
/* @var $c junk */
$c = mysqli_free_result($result);
/* @var $c1 junk */
$c1 = mysqli_close($con);
?>
<div id="menu">
<a href="menu.php" ><div id='button'>Main Menu</div></a>
<footer >
<a href="water_change.php"><div id='button'/>Water Changes</div></a>
<a href="water.php"><div id='button'/>Water Testing</div> </a>
<a href="maintenance.php"><div id='button'/>Maintenance</div></a>
<a href="livestock.php"><div id='button'/>Livestock</div></a>
<a href="plants.php"><div id='button'/>Plants</div></a>
<a href="log.php"><div id='button'/>Log</div></a>
<a href="tank.php"><div id='button'/>Tanks</div></a>
<a href="filter.php"><div id='button'/>Filters</div></a>
<a href="pump.php"><div id='button'/>Pumps</div></a>
<a href="light.php"><div id='button'/>Lights</div></a>
<a href="accessory.php"><div id='button'/>Accessories</div></a>
<a href="diary.php"><div id='button'/>Diary</div></a>
</footer>
</div>
</div>
</div>
</body>
</html>