【发布时间】：2015-10-30 22:42:23
【问题描述】：
所以我遇到了下拉选择框的问题。我正在做的是让某人登录数据库，然后数据库显示选择框中的所有可用表。然后，用户可以选择他们希望查看的表格，点击选择然后砰！有表信息。
但是，我在选择框中的数据在点击选择后仍然存在问题。出于某种原因，它只是让它空了。我正在使用会话变量，也许这会影响它？我现在才刚刚开始学习它是如何工作的。看看让我知道你的想法：
<?php
session_start();
if(!isset($_SESSION['session_level'])):
$_SESSION['session_level'] = 0; ?>
<? endif ?>
<?php
if(isset($_POST['host'])):
$_SESSION['host'] = $_POST['host'];
$_SESSION['dbname'] = $_POST['dbname'];
$_SESSION['username'] = $_POST['username'];
$_SESSION['pw'] = $_POST['pw'];
?>
<?php endif ?>
<!DOCTYPE html>
<html>
<head>
<meta charset='utf-8' />
<title>Login Test</title>
</head>
<body>
<?
if (isset($_POST['return']))
{
$_SESSION['session_level'] = 0;
}
else if (isset($_POST['submit']))
{
try
{
$db = new PDO("mysql:host=".$_POST['host'].";dbname=".$_POST['dbname'], $_POST['username'], $_POST['pw']);
}
catch(Exception $error)
{
$_SESSION['session_level'] = 0;?>
<a href='<?= $_SERVER['PHP_SELF'] ?>'>Click here to return.</a>
<? echo "\n"; ?>
<?die("Connection to user database failed: " . $error->getMessage());
}
try
{
$db->setAttribute(PDO::ATTR_ERRMODE, PDO:: ERRMODE_EXCEPTION);
$query = "SHOW TABLES";
$results = $db->query($query)->fetchAll();
$_SESSION['session_level'] = 1;
}
catch(Exception $error)
{
echo "Problem with query!";
$_SESSION['session_level'] = 0;?>
<a href='<?= $_SERVER['PHP_SELF'] ?>'>Click here to return.</a>
<? }
}
?>
<?php if($_SESSION['session_level'] == 0){?>
<h1>Database Practice</h1>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post" name='initialentry'>
<table border='0' style='text-align: center'>
<tr>
<td style='text-align: right;'>Enter host name:</td>
<td style='text-align: left;'>
<input type='text' name='host' value='localhost'>
</td>
</tr>
<tr>
<td style='text-align: right;'>Enter database name:</td>
<td style='text-align: left;'>
<input type='text' name='dbname' value='zxyx999'>
</td>
</tr>
<tr>
<td style='text-align: right;'>Enter user name:</td>
<td style='text-align: left;'>
<input type='text' name='username' value='zxyx999'>
</td>
</tr>
<tr>
<td style='text-align: right;'>Enter password:</td>
<td style='text-align: left;'>
<input type='password' name='pw' width='15' value='12345'>
</td>
</tr>
<tr>
<td style='text-align: right;'><input type="reset" name="reset" value="Reset"></td>
<td style='text-align: left;'><input type="submit" name="submit" value="Submit"></td>
</tr>
</table>
</form>
<?php }
else if ($_SESSION['session_level'] == 1)
{
?>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post" name='getForm'>
<select name='select'>
<? foreach($results as $row)
echo "<option value=" . $row[0] .">" .$row[0]. "</option>"; ?>
</select>
<input type="submit" name="selected" value="Select">
<input type="submit" name="return" value="Return to Main Screen">
</form>
<?php
if(isset($_POST['selected']))
{
try
{
$db = new PDO("mysql:host=".$_SESSION['host'].";dbname=".$_SESSION['dbname'], $_SESSION['username'], $_SESSION['pw']);
}
catch(Exception $error)
{
die("Connection to user database failed: " . $error->getMessage());
}
try
{
$query = $db->prepare("SELECT * FROM " . $_POST['select']);
$query->execute();
$header = true;
}
catch(Exception $error)
{
echo "Query failed.";
}
echo "</br>";
?>
<?php
echo "<table border='1'>";
while ($row = $query->fetch(PDO::FETCH_ASSOC))
{
echo "<tr>";
if($header == 'true')
{
foreach($row as $index => $fieldValue)
{
echo "<td>";
echo $index;
echo"</td>";
}
echo "</tr>";
$header = 'false';
}
echo "<tr>";
foreach($row as $index => $fieldValue)
{
echo "<td>";
echo $fieldValue;
echo "</td>";
}
echo "</tr>";
}
echo "</table>";
}
}
?>
</body>
</html>
【问题讨论】：