Mysql 集成随机唯一id mysql unique number generation

一句代码：

SELECT FLOOR(10000 + RAND() * 89999) AS random_number
FROM table1
WHERE "random_number" NOT IN (SELECT unique_id FROM table2)
LIMIT 1

 

随机生成5位数字，并且不重复。上面的代码真是给人无限的联想力。

 

例如：

function get_unique_username($chance=10,$show_sql=FALSE)
{
    global $conn;
    
    // connect db
    if(!$conn) connect();
    
    $output = FALSE;
    $rand   = rand(1,$chance);
    
    $sql = 'SELECT FLOOR('.($rand==5?'10000 + RAND() * 89999':'100000 + RAND() * 899999').') AS random_number FROM gm_users WHERE "random_number" NOT IN (SELECT unique_id FROM gm_ids) LIMIT 1';
    if($show_sql) echo $sql;
    
    $result = mysql_query($sql);
    $row    = mysql_fetch_assoc($result);
    
    if($row['random_number']) 
    {
        $output = $row['random_number'];

        // insert this random_number to table gm_ids
        insert('gm_ids', array('unique_id'=>$output));
    }
    
    return $output;
}

 

以上实例为，随机生成5或6位数字，并且生成5位数字的记录是 1/10 （$chance）

 

原创 http://justcode.ikeepstudying.com/2015/05/mysql-%E9%9B%86%E6%88%90%E9%9A%8F%E6%9C%BA%E5%94%AF%E4%B8%80id-mysql-unique-number-generation/