Question

每当我使用：while($x = mysqli_fetch_array($y))然后echo $x时，它将返回除第一行之外的所有内容。

表格：

的 forum.users

users.user_id
users.username
USERS.PASSWORD
users.image

forum.forums

forums.forum_id
forums.user_id
forums.name

这是我的代码：

<?php
session_start();
$con = new mysqli("localhost", "root", "", "forum");
if(!isset($_SESSION["online"])==1)  {
    $_SESSION["offline"] = "true";
}
$username = $_SESSION["online"];
$u_query = "SELECT * FROM forum.users WHERE users.username = '".$username."'";
$u_result = $con -> query($u_query);
$u_row = mysqli_fetch_array($u_result);
if(isset($_POST["logout"])) {
    session_unset();
    session_destroy();
    header("Location: login.php");
}   
$f_search = "SELECT * FROM forum.forums WHERE user_id = '".$u_row['user_id']."'";
$f_result = $con -> query($f_search);
$f_row = mysqli_fetch_array($f_result);
?>
<html>
<head>
<title>Home</title>
<charset = "UTF-8">
<link href="style.css" rel="stylesheet" type="text/css">
</head> 
<body>

<div id="header">
    <div id="user">
        <img src="<?php echo $u_row['image']; ?>" id="user-image">
        <?php echo $u_row["username"]; ?>
        <form method="post">
            <input type="submit" name="logout" value="sign out">
        </form> 
    </div>
</div>

<?php if(mysqli_num_rows($f_result)>= 0) { ?>
<div>
    <div>Your forums:</div><table><tr>
    <?php while($f_row = mysqli_fetch_array($f_result)) { ?>
    <td><a href="forum.php?forumid=<?php echo $f_row['forum_id']; ?>"><?php echo $f_row["name"]; ?></a></td>
    <td></td>
    <?php } ?>
    </tr></table>
</div>
<?php } ?>
</body>
</html>

为什么不返回第一行？

Answer 1

调用mysqli_fetch_array获取行并前进光标。所以你的第一个

$f_row = mysqli_fetch_array($f_result);

有第一行。然后

while($f_row = mysqli_fetch_array($f_result)) {

前进到第二行，并循环显示所有其他结果。

因此，要么摆脱$f_row = mysqli_fetch_array($f_result);之外的while，要么输出while之前的内容。它看起来不像你正在使用那个阵列所以我只是删除它。

此外：

$username = $_SESSION["online"];
$u_query = "SELECT * FROM forum.users WHERE users.username = '".$username."'";

对SQL注入开放。您应该使用预准备语句并参数化查询。 http://php.net/manual/en/mysqli.quickstart.prepared-statements.php

Answer 2

删除$f_row = mysqli_fetch_array($f_result);

通过在脚本的早期调用它，你正在推进指针+1。然后在你的while($f_row = mysqli_fetch_array($f_result))中，你实际上从第二行开始。

$f_search = "SELECT * FROM forum.forums WHERE user_id = '".$u_row['user_id']."'";
$f_result = $con -> query($f_search);
$f_row = mysqli_fetch_array($f_result); // <---- remove this line

sql查询不返回第一行

2 个答案: