array_filter、find_in_set查询id是否在id集合中、concat连接字符串，ifnull、if用法

1：array_filter检查每个元素是不是数字 

if(array_filter($this->data['log_id'] ,'is_numeric') !== $data['log_id']) echo '000';

2：concat连接字符串，ifnull、if用法
update log
set users = concat(ifnull(users,''),if(users,',411','411'))
where log_id between 453729 and 453740;

3：find_in_set查询id是否在id集合中
SELECT
    *
FROM
    log
WHERE
    log_id BETWEEN 453729
AND 453740 and !find_in_set('2',ifnull(l.users,""));