创建用于导航的下一个和上一个按钮 [英] Creating Next and Previous buttons for navigation

问题描述

我正在尝试在页面上创建下一个和上一个按钮.我使用 id 从数据库中调用信息，并使用 id 变量选择新行和上一行.

I am trying to create next and previous buttons on a page. I am using the id to call the information from the database and also using the id variable to choose the new and previous row.

它适用于下一个按钮，但上一个按钮一直返回 1 的 id.

It works for the next button, but the previous button keeps returning an id of 1.

这是我在 php 中的函数:

This is my function in php:

function getNavLinks($subj) {
global $connection;
$query = "SELECT 
( SELECT id FROM artists WHERE id > " . $subj . " LIMIT 1 )
AS nextValue,
( SELECT id FROM artists WHERE id < " . $subj . " LIMIT 1 )
AS prevValue
FROM artists";
$result_set = mysql_query($query, $connection);
confirmQuery($result_set);
//if no rows are returned, fetch array will return false.
if ($Links = mysql_fetch_array($result_set)) {
    return $Links;
}
else {
    return NULL;
}
}

我在 html 头中这样调用它:

and I am calling it in the html head like this:

<?php
$subj = $_GET['subj'];
$navLink = getNavLinks($subj);
?>

在这样的身体中:

<?php echo "<a href=\"artist.php?subj=" . urlencode($navLink['prevValue']) . "\">Prev</a>"; ?>&nbsp;
<?php echo "<a href=\"artist.php?subj=" . urlencode($navLink['nextValue']) . "\">Next</a>"; ?>

为什么 $navLink['prevValue'] 返回值 1?

Why is the $navLink['prevValue'] returning a value of one?

任何帮助都会很棒！

推荐答案

你需要把你的SQL语句改成这样:

You need to change your SQL statement to this:

"SELECT 
( SELECT id FROM artists WHERE id > '$subj' LIMIT 1 )
AS nextValue,
( SELECT id FROM artists WHERE id < '$subj' ORDER BY id DESC LIMIT 1 )
AS prevValue
FROM artists" 

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