$where = array("tag"=>array("EQ","Windows7"));
M("Tags")->where($where)->setInc("hits");

按理，生成的SQL应该是：
UPDATE `shuipf_tags` SET `hits`=hits+1 WHERE ( `tag` = 'Windows7' )
在3.1.2也确实如此，刚刚升级到3.1.3后发现，就变成这样了

UPDATE `shuipf_tags` SET WHERE ( `tag` = 'Windows7' )

`hits`=hits+1 没了-__,-!