Php 点击链接时Mysql字段数据不显示？

如果单击链接，我将尝试从数据库中获取数据

我使用了这个示例中建议的示例代码-

但是当我点击一个链接时，它就不起作用了，什么也没有出现

main.php

<?php
include('conn.php');
$sql2    = "SELECT Title FROM addpromo";
$result2 = mysql_query($sql2);

echo "<div id=\"links\">\n";
echo "<ul>\n";
while ($row2 = mysql_fetch_assoc($result2)) {
    echo "<li> <a href=\"fullproject.php?title=\""
        . urlencode($row2['Title']) . "\">"
        . htmlentities($row2['Title']) . "</a>\n</li>";
}
echo "</ul>";
echo "</div>";
?>

<?php
// Connect to server.
include('conn.php');
$projectname = isset($_GET['Title']);
$sql1 = "SELECT Title FROM addpromo WHERE Title = '$projectname'";
$result1 = mysql_query($sql1);

while ($row1 = mysql_fetch_assoc($result1)) {
    echo "Project Name: " . $row1['Title'] . "<br />";
    echo "<br /> ";
}
?>

<?php
include('conn.php');
$sql2="SELECT Title FROM addpromo";
$result2=mysql_query($sql2);    

echo '<div id="links">';
echo '<ul>';
while($row2 = mysql_fetch_assoc($result2)){
echo '<li><a href="fullproject.php?title='.urlencode($row2['Title']).'">'.htmlentities($row2['Title']).'</a></li>';

}
echo '</ul>';
echo '</div>';
?>

<?php

if(isset($_GET['title'])){

    include('conn.php');

    $projectname= $_GET['title'];

    $sql1="SELECT Title FROM addpromo WHERE Title = '$projectname'";
    $result1=mysql_query($sql1);    

    while($row1 = mysql_fetch_assoc($result1)) {
      echo "Project Name: " . $row1['Title']. "<br />";    
      echo "<br /> ";
    }

}

?>

这显示正确。但是当我点击一个链接时，fullproject.php中没有显示任何内容，只有一个空白页面

fullproject.php

<?php
include('conn.php');
$sql2    = "SELECT Title FROM addpromo";
$result2 = mysql_query($sql2);

echo "<div id=\"links\">\n";
echo "<ul>\n";
while ($row2 = mysql_fetch_assoc($result2)) {
    echo "<li> <a href=\"fullproject.php?title=\""
        . urlencode($row2['Title']) . "\">"
        . htmlentities($row2['Title']) . "</a>\n</li>";
}
echo "</ul>";
echo "</div>";
?>

<?php
// Connect to server.
include('conn.php');
$projectname = isset($_GET['Title']);
$sql1 = "SELECT Title FROM addpromo WHERE Title = '$projectname'";
$result1 = mysql_query($sql1);

while ($row1 = mysql_fetch_assoc($result1)) {
    echo "Project Name: " . $row1['Title'] . "<br />";
    echo "<br /> ";
}
?>

<?php
include('conn.php');
$sql2="SELECT Title FROM addpromo";
$result2=mysql_query($sql2);    

echo '<div id="links">';
echo '<ul>';
while($row2 = mysql_fetch_assoc($result2)){
echo '<li><a href="fullproject.php?title='.urlencode($row2['Title']).'">'.htmlentities($row2['Title']).'</a></li>';

}
echo '</ul>';
echo '</div>';
?>

<?php

if(isset($_GET['title'])){

    include('conn.php');

    $projectname= $_GET['title'];

    $sql1="SELECT Title FROM addpromo WHERE Title = '$projectname'";
    $result1=mysql_query($sql1);    

    while($row1 = mysql_fetch_assoc($result1)) {
      echo "Project Name: " . $row1['Title']. "<br />";    
      echo "<br /> ";
    }

}

?>

有人能帮我解决这个问题吗，或者用其他方法（如果单击链接，从数据库获取数据）解决这个问题吗？

更改为这个

main.php

<?php
include('conn.php');
$sql2    = "SELECT Title FROM addpromo";
$result2 = mysql_query($sql2);

echo "<div id=\"links\">\n";
echo "<ul>\n";
while ($row2 = mysql_fetch_assoc($result2)) {
    echo "<li> <a href=\"fullproject.php?title=\""
        . urlencode($row2['Title']) . "\">"
        . htmlentities($row2['Title']) . "</a>\n</li>";
}
echo "</ul>";
echo "</div>";
?>

<?php
// Connect to server.
include('conn.php');
$projectname = isset($_GET['Title']);
$sql1 = "SELECT Title FROM addpromo WHERE Title = '$projectname'";
$result1 = mysql_query($sql1);

while ($row1 = mysql_fetch_assoc($result1)) {
    echo "Project Name: " . $row1['Title'] . "<br />";
    echo "<br /> ";
}
?>

<?php
include('conn.php');
$sql2="SELECT Title FROM addpromo";
$result2=mysql_query($sql2);    

echo '<div id="links">';
echo '<ul>';
while($row2 = mysql_fetch_assoc($result2)){
echo '<li><a href="fullproject.php?title='.urlencode($row2['Title']).'">'.htmlentities($row2['Title']).'</a></li>';

}
echo '</ul>';
echo '</div>';
?>

<?php

if(isset($_GET['title'])){

    include('conn.php');

    $projectname= $_GET['title'];

    $sql1="SELECT Title FROM addpromo WHERE Title = '$projectname'";
    $result1=mysql_query($sql1);    

    while($row1 = mysql_fetch_assoc($result1)) {
      echo "Project Name: " . $row1['Title']. "<br />";    
      echo "<br /> ";
    }

}

?>

fullproject.php

<?php
include('conn.php');
$sql2    = "SELECT Title FROM addpromo";
$result2 = mysql_query($sql2);

echo "<div id=\"links\">\n";
echo "<ul>\n";
while ($row2 = mysql_fetch_assoc($result2)) {
    echo "<li> <a href=\"fullproject.php?title=\""
        . urlencode($row2['Title']) . "\">"
        . htmlentities($row2['Title']) . "</a>\n</li>";
}
echo "</ul>";
echo "</div>";
?>

<?php
// Connect to server.
include('conn.php');
$projectname = isset($_GET['Title']);
$sql1 = "SELECT Title FROM addpromo WHERE Title = '$projectname'";
$result1 = mysql_query($sql1);

while ($row1 = mysql_fetch_assoc($result1)) {
    echo "Project Name: " . $row1['Title'] . "<br />";
    echo "<br /> ";
}
?>

<?php
include('conn.php');
$sql2="SELECT Title FROM addpromo";
$result2=mysql_query($sql2);    

echo '<div id="links">';
echo '<ul>';
while($row2 = mysql_fetch_assoc($result2)){
echo '<li><a href="fullproject.php?title='.urlencode($row2['Title']).'">'.htmlentities($row2['Title']).'</a></li>';

}
echo '</ul>';
echo '</div>';
?>

<?php

if(isset($_GET['title'])){

    include('conn.php');

    $projectname= $_GET['title'];

    $sql1="SELECT Title FROM addpromo WHERE Title = '$projectname'";
    $result1=mysql_query($sql1);    

    while($row1 = mysql_fetch_assoc($result1)) {
      echo "Project Name: " . $row1['Title']. "<br />";    
      echo "<br /> ";
    }

}

?>

这是存储一个布尔值

$projectname=isset（$\u GET['Title']），无论是否设置了标题。而是使用
$projectname=$\u GET['Title']
isset返回一个布尔值（真/假），您需要变量的实际值：

$projectname= $_GET['title'];

此外，您必须只传递标题作为URL参数，而不将其括在引号中。所以这一行有一个错误：

echo "<li> <a href=\"fullproject.php?title=" . urlencode($row2['Title']) . "\">"

echo“
”

请注意，title=
之后缺少\“，请将$projectname=isset（$\u GET['title']）更改为$projectname=$\u GET['title']；as isset返回一个布尔值谢谢，但当我删除isset时，它将错误显示为未定义的索引：Titlethanks，但当我删除isset时，它将错误显示为未定义的索引：TitleGood point，该参数以小写形式发送：title。我相应地更改了答案。好的，在代码中发现了另一个问题。这次是在main.php中。我将G执行以下步骤：1.检查链接的URL是否正常，包括标题参数。2.在fullproject.php中调试收到的参数。为此，您可以使用print\r（$\u GET）。代码中有一点错误（括号），但我更新了我的答案$sql1=“从addpromo中选择标题，其中标题='$projectname'"; 这有什么意义？您正在选择例如title\u x\u name，其中title=title\u x\u name当您单击链接时，您的url是否正确？fullproject.php？title=选定的_title更改为该回显“
\n
”@梅尔文：很抱歉更改为：echo'
'；谢谢，但是当我删除isset时，它显示了一个错误作为未定义的索引：Title