<PHP>如何在没有自动增量的情况下生成唯一字段

Question

i'm trying to generate a unique id using this code:

$RCode = md5(uniqid(rand(), true));

then i want it to check in my database if the RCode is unique.

if it isnt i want it to use that part of the code again and check in my database again if it is unique,

if it is unique it should write to my database.

i have all the code i need for checking and writing into the database, i just have no idea how to make it loop back to the start.

Help is appreciated!

Thanks a lot in advance!

Answer 1

Typical example for do-while loop.

Some PHP-pseudocode:

do {
    $rcode = md5(uniqid(rand(), true));
    $res = mysql_result(mysql_query("SELECT COUNT(*) FROM records WHERE rcode='$rcode'"));
} while ($res[0] > 0);

mysql_query("INSERT INTO records (rcode) VALUES ('$rcode')");