警告:mysqli_query():无法获取mysqli [英] Warning: mysqli_query(): Couldn't fetch mysqli
问题描述
我有一个问题,我无法从MySQL数据库(通过PHP)检索结果.我在其他地方使用了相同的功能,并且可以正常工作.但是在这一点上,我不断收到警告:mysqli_query():无法获取mysqli"错误.问题的详细内容在下面说明. 我在PHP的其他地方(如下所示的getAllCountries)使用了一个非常类似的函数,该函数运行良好:
I have a problem where I can not retrieve the result from my MySQL database (via PHP). I use the same function in other places and it works flawlessly. However at this point i keep getting the "Warning: mysqli_query(): Couldn't fetch mysqli" error. Details of the problem are explained below. I use a quite similar function elsewhere (getAllCountries as seen below) in my PHP which does work perfectly:
function getAllCountries()
{
$result = db_query("SELECT countryid, name FROM country ORDER BY name ASC");
echo "<select class=addresscountry name=country>";
while($row = mysqli_fetch_array($result)) {
echo '<option value="' . $row['countryid'] . '">' . $row['name'] . '</option>';
}
echo "</select>";
mysqli_close(db_connect());
}
所以问题出在下面:
我有一个包含以下代码的php文件:
I have a php file containing the following code:
<?php
require 'includes/functions.php';
function getUserPicPath()
{
$userid = $_SESSION['userid'];
$result = db_query("SELECT picture FROM user WHERE userid='$userid'");
while($row = mysqli_fetch_array($result)) {
$picturepath = $row['picture'];
}
echo $picturepath;
mysqli_close(db_connect());
}
我的functions.php文件具有以下行(以及其他不相关的函数):
my functions.php file has the following line (together with other non-relevant functions):
require 'dbfunctions.php';
和我的dbfunctions.php看起来像这样:
and my dbfunctions.php looks like this:
<?php
function db_connect()
{
require ".db_password.php";
static $connection;
if(!isset($connection)) {
$connection = mysqli_connect('localhost',$username,$password,$dbname);
}
if($connection === false) {
return mysqli_connect_error();
}
return $connection;
}
function db_query($query)
{
$connection = db_connect();
$result = mysqli_query($connection,$query);
return $result;
}
在我的PHP文档中,我调用了以下函数:
In my PHP document I call the following function :
if ($userid == -1)
{
showNotAuthorizedPage();
} else {
myAccountPage();
}
并且myAccountPage()函数与getUserPicPath()函数在同一文件中声明,此getUserPicPath()函数的调用方式如下:
and the myAccountPage() function is declared in the same file as the getUserPicPath() function, this getUserPicPath() function is called as follows:
<div id="tabs-2">
<p><?php getUserPicPath(); ?></p>
</div>
我在网页上使用了标签( http://jqueryui.com/tabs/#default ),即我想在哪里打电话. myAccountPage()函数给出以下错误:
I use the tabs (http://jqueryui.com/tabs/#default) on my webpage and that is where i want to call it in. The myAccountPage() function which gives the following error :
Warning: mysqli_query(): Couldn't fetch mysqli in C:\Users\Dennis\Documents\My Dropbox\xxx\zzz\www\Project Files\includes\dbfunctions.php on line 29
Call Stack
# Time Memory Function Location
1 0.0000 256880 {main}( ) ..\myaccount.php:0
2 0.0010 283328 myAccountPage( ) ..\myaccount.php:181
3 0.0070 285368 getUserPicPath( ) ..\myaccount.php:121
4 0.0070 285528 db_query( ) ..\myaccount.php:11
5 0.0070 285624 mysqli_query ( ) ..\dbfunctions.php:29
( ! ) Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, null given in C:\Users\Dennis\Documents\My Dropbox\me&roxy\WE\final project\Project Files\myaccount.php on line 13
Call Stack
# Time Memory Function Location
1 0.0000 256880 {main}( ) ..\myaccount.php:0
2 0.0010 283328 myAccountPage( ) ..\myaccount.php:181
3 0.0070 285368 getUserPicPath( ) ..\myaccount.php:121
4 0.0080 285768 mysqli_fetch_array ( ) ..\myaccount.php:13
( ! ) Notice: Undefined variable: picturepath in C:\Users\Dennis\Documents\My Dropbox\me&roxy\WE\final project\Project Files\myaccount.php on line 17
Call Stack
# Time Memory Function Location
1 0.0000 256880 {main}( ) ..\myaccount.php:0
2 0.0010 283328 myAccountPage( ) ..\myaccount.php:181
3 0.0070 285368 getUserPicPath( ) ..\myaccount.php:121
( ! ) Warning: mysqli_close(): Couldn't fetch mysqli in C:\Users\Dennis\Documents\My Dropbox\me&roxy\WE\final project\Project Files\myaccount.php on line 19
Call Stack
# Time Memory Function Location
1 0.0000 256880 {main}( ) ..\myaccount.php:0
2 0.0010 283328 myAccountPage( ) ..\myaccount.php:181
3 0.0070 285368 getUserPicPath( ) ..\myaccount.php:121
4 0.0100 285864 mysqli_close ( ) ..\myaccount.php:19
推荐答案
我认为这是因为第一次关闭数据库连接时,您会忘记这样做:
I think it is because when you close the database connection the first time, you forget to do:
unset($connection);
然后,当您再次尝试连接数据库时,由于它仍设置为关闭的连接,因此它突然消失了.
And then when you try connecting to the database again, it craps out because it is still set to the closed connection.
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