[英]php function with a while-loop
I have a function that generates a random combination. 我有一个生成随机组合的函数。
my function looks like this: 我的函数看起来像这样:
function random_gen($length) {
$random= "";
srand((double)microtime()*1000000);
$char_list = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
$char_list .= "abcdefghijklmnopqrstuvwxyz";
$char_list .= "1234567890";
// Add the special characters to $char_list if needed
for($i = 0; $i < $length; $i++)
{
$random .= substr($char_list,(rand()%(strlen($char_list))), 1);
}
return $random;
}
$new_url = random_gen(6);
Now i would like to have a while-loop that checks if $new_url already exist in my database... 现在我想有一个while循环来检查$ new_url是否已经存在于我的数据库中...
And then insert the result like this: 然后插入如下结果:
mysql_query("INSERT INTO lank (url, code) VALUES ('$url', '$new_url')");
I got everything to work except the while-loop. 除了while循环外,我所有工作都可以进行。 and i just cant figure out how to do it...
我只是想不通怎么做...
mysql_affected_rows()
if the INSERT actually happened or not (ie code already present) mysql_affected_rows()
检查INSERT是否实际发生(即代码已经存在) saves you a SELECT query 为您节省一个SELECT查询
while ( true ) {
$new_url = random_gen(6);
mysql_query("INSERT INTO lank (url, code) VALUES ('$url', '$new_url')");
if ( mysql_affected_rows() )
break;
}
Use this random_generator 使用这个random_generator
function random_gen($length) {
$characters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
$string = '';
for ($i = 0; $i < $length; $i++) {
$string .= $characters[rand(0, strlen($characters) - 1];
}
return $string;
}
您不需要while循环,只需执行查询
mysql_query("SELECT COUNT(*) FROM lank WHERE code = {$new_url}");
It's pretty straight forward: 这很简单:
$sql = "SELECT COUNT(*) as num FROM lank WHERE code='{$new_url}'";
$result = mysql_query($sql);
$row = mysql_fetch_assoc($result);
while($row['num'] > 0) {
$new_url = random_gen(6);
$sql = "SELECT COUNT(*) as num FROM lank WHERE code='{$new_url}'";
$result = mysql_query($sql);
$row = mysql_fetch_assoc($result);
}
This should work, without repeating code: 这应该有效,无需重复代码:
while(true) {
$new_url = random_gen(6);
$sql = "SELECT COUNT(*) FROM lank WHERE code='{$new_url}'";
$result = mysql_query($sql);
$row = mysql_fetch_row($result);
if (!$row[0])
break;
}
Use the uniqid()
function instead. 请改用
uniqid()
函数。 It will always generate a random result. 它将始终生成随机结果。
If you need more security (ie: you don't want adjacent values), simply hash the output: sha1(uniqid())
. 如果需要更高的安全性(即:不需要相邻的值),只需对输出进行哈希处理:
sha1(uniqid())
。
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