[英]PHP - MySQLi Prepared Statements
$name = $_GET['user'];
if(isset($_GET['user']) && strlen($_GET['user'])>0) {
$mysqli = new mysqli($dbhost, $dbuser, $dbpass, $db);
$stmt = $mysqli->prepare("SELECT username FROM users WHERE username=?");
$stmt->bind_param('s', $name);
$stmt->execute();
while($stmt->fetch()) {
if($stmt->num_rows == 0) {
header("Location: home?errormsg=notfound");
exit();
}
}
$stmt->store_result();
$stmt->close();
}
$mysqli->close();
So, the above code checks if $_GET['name'] exists in the database, and if it doesn't, to redirect to home?errormsg=notfound but it redirects the usernames which exists in the database to the link 'home?errormsg=notfound' as well. 因此,上面的代码检查$ _GET ['name']是否存在于数据库中,如果不存在,则重定向到home?errormsg = notfound,但它将数据库中存在的用户名重定向到链接“ home”。 errormsg = notfound”。 Can you suggest a way to solve this problem?
您能提出解决此问题的方法吗?
You have to call $stmt->store_result()
before $stmt->num_rows
. 您必须在
$stmt->num_rows
之前调用$stmt->store_result()
。
And your $stmt->fetch()
is not necessary, because you don't use the selected data. 而且您不需要
$stmt->fetch()
,因为您不使用所选数据。
If you call store_result()
after num_rows
it won't work. 如果您在
num_rows
之后调用store_result()
,它将不起作用。
Part of comment from manual page : 手册页的部分评论:
If you do not use mysqli_stmt_store_result( ), and immediatley call this function after executing a prepared statement, this function will usually return 0 as it has no way to know how many rows are in the result set as the result set is not saved in memory yet.
如果您不使用mysqli_stmt_store_result(),并且在执行准备好的语句后立即调用此函数,则该函数通常将返回0,因为它无法知道结果集中有多少行,因为结果集未保存在内存中然而。
So your code should look like this: 因此,您的代码应如下所示:
$name = $_GET['user'];
if(isset($_GET['user']) && strlen($_GET['user'])>0) {
$mysqli = new mysqli($dbhost, $dbuser, $dbpass, $db);
$stmt = $mysqli->prepare("SELECT username FROM users WHERE username=?");
$stmt->bind_param('s', $name);
$stmt->execute();
$stmt->store_result();
if($stmt->num_rows == 0) {
header("Location: home?errormsg=notfound");
exit();
}
$stmt->close();
}
$mysqli->close();
I have not tried this but maybe it helps. 我没有尝试过,但也许有帮助。
You are calling $stmt->store_result();
您正在调用
$stmt->store_result();
after $stmt->num_rows
在
$stmt->num_rows
Please try moving $stmt->store_result();
请尝试移动
$stmt->store_result();
before $stmt->num_rows
在
$stmt->num_rows
之前
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