上传信息时，我需要不需要我的表单字段。以下是场景和代码：
场景：用户想要编辑他们的信息，而不更新不同的图像：但很明显，当我点击提交并将图像字段留空时，会出现错误，我该如何防止这种情况发生。
我想不需要的字段是图像字段（照片）
这是代码：
<?php
session_start();
$UserName = $_SESSION['UserName'];
require("checkLoginSession.php");
$adminid = $_GET['id'];
//removed connection
$tbl_name="admin"; // Table name
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
echo("Logged In As: $UserName");
echo "<br />";
echo("We are editing Data for ID: $adminid");
echo "<br />";
echo "<a href=test.php>Go back to panel</a>";
$id=$_GET['id'];
// Retrieve data from database
$sql="SELECT * FROM admin WHERE id='$id'";
$result=mysql_query($sql) or die(mysql_error());
$rows=mysql_fetch_array($result);
?>
<table width="400" border="0" cellspacing="1" cellpadding="0">
<tr>
<form enctype="multipart/form-data" name="form1" method="post" action="update_ac.php">
<td>
<table width="100%" border="0" cellspacing="1" cellpadding="0">
<tr>
<td> </td>
<td colspan="3"><strong>Update data in mysql</strong> </td>
</tr>
<tr>
<td align="center"> </td>
<td align="center"> </td>
<td align="center"> </td>
<td align="center"> </td>
</tr>
<tr>
<td align="center"> </td>
<td align="center"><strong>Name</strong></td>
<td align="center"><strong>Main Content</strong></td>
<td align="center"><strong>Image Locatoin</strong></td>
</tr>
<tr>
<td> </td>
<td align="center"><input name="name" type="text" id="name" value="<? echo $rows['name']; ?>"></td>
<td align="center"><input name="mainContent" type="text" id="mainContent" value="<? echo $rows['mainContent']; ?>" size="15"></td>
<td align="center"><input name="photo" type="file" id="photo">
</tr>
<tr>
<td> </td>
<td><input name="id" type="hidden" id="id" value="<? echo $rows['id']; ?>"></td>
<td align="center"><input type="submit" name="Submit" value="Submit"></td>
<td> </td>
</tr>
</table>
</td>
</form>
</tr>
</table>
<?
mysql_close();
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Jonathon Legg - University Year Book - Edit Page</title>
</head>
<body>
<h2>Edit Page (<?php echo ("$adminid"); ?>)</h2>
<a href="test.php"><img src="backtopanel.jpg" alt="back to panel" width="454" height="85" border="0" longdesc="back to panel" /></a>
</body>
</html>
这是update_acknowledge.php
<?php
session_start();
$UserName = $_SESSION['UserName'];
require("checkLoginSession.php");
include "common.php";
DBConnect();
$Link = mysql_connect($Host, $User, $Password);
//connection removed for stack overflow //
$tbl_name="admin"; // Table name
$target = "images/";
$target = $target . basename( $_FILES['photo']['name']);
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
// update data in mysql database
$_POST = array_map("mysql_real_escape_string", $_POST);
$firstName = $_POST["name"];
$mainText = $_POST["mainContent"];
$pic=($_FILES['photo']['name']);
//
$sql="UPDATE admin SET name='$firstName', mainContent='$mainText', photo='$pic' WHERE id='$id'";
//
if (mysql_db_query ($DBName, $sql, $Link)){
print ("A record was created <br><a href=index.php> return to index </a>'n");
//Writes the photo to the server
if(move_uploaded_file($_FILES['photo']['tmp_name'], $target))
{
//Tells you if its all ok
echo "The file ". basename( $_FILES['uploadedfile']['name']). " has been uploaded, and your information has been added to the directory";
}
else {
//Gives and error if its not
echo "Sorry, there was a problem uploading your file.";
}
} else {
print ("Record not created");
}
mysql_close($Link);
?>
只需包装一个"if"语句。。。
if (!empty($_FILES['photo']['name'])) {
$pic=mysql_real_escape_string($_FILES['photo']['name']);
$sql="UPDATE admin SET name='$firstName', mainContent='$mainText', photo='$pic' WHERE id='$id'";
} else {
$sql="UPDATE admin SET name='$firstName', mainContent='$mainText' WHERE id='$id'";
}
当然，在moveuploadedfile块上也需要类似的if语句。
我已将图像逻辑置于条件if（$_FILES['photo']['error']==0）中
<?php
session_start();
$UserName = $_SESSION['UserName'];
require("checkLoginSession.php");
include "common.php";
DBConnect();
$Link = mysql_connect($Host, $User, $Password);
//connection removed for stack overflow //
$tbl_name="admin"; // Table name
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
// update data in mysql database
$_POST = array_map("mysql_real_escape_string", $_POST);
$firstName = $_POST["name"];
$mainText = $_POST["mainContent"];
//
$sql = "UPDATE admin SET name='$firstName', mainContent='$mainText'";
if($_FILES['photo']['error'] == 0) {
$target = "images/";
$target = $target . basename( $_FILES['photo']['name']);
$pic=($_FILES['photo']['name']);
$sql .= ", photo='$pic'";
}
$sql .= "WHERE id='$id'";
//
if (mysql_db_query ($DBName, $sql, $Link)) {
print ("A record was created <br><a href=index.php> return to index </a>'n");
if($_FILES['photo']['error'] == 0) {
//Writes the photo to the server
if(move_uploaded_file($_FILES['photo']['tmp_name'], $target)) {
//Tells you if its all ok
echo "The file ". basename( $_FILES['uploadedfile']['name']). " has been uploaded, and your information has been added to the directory";
} else {
//Gives and error if its not
echo "Sorry, there was a problem uploading your file.";
}
}
} else {
print ("Record not created");
}
mysql_close($Link);
?>