SQL报错，You have an error in your SQL syntax; check the manual that corresponds to

SQL报错了，
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1---Resource id #9----SELECT imei from messagelog where mac in ()
PHP代码：

$mac.="'".$value."',";$listimei = $db->query("SELECT imei from messagelog where mac in ($mac) ")->fetchList();

不知道哪个地方有问题，求大神帮忙

回复讨论(解决方案)

试试

$listimei = $db->query("SELECT imei from messagelog where mac in ('$value') ")->fetchList();

你的 $mac 为空
实际执行的是 SELECT imei from messagelog where mac in ( )
这就要出错了：
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')'

$mac最后多一个逗号