查询timestamp类型数据

 $where=" roleid = 8 and lizhi = 0 and branchid IN (".implode(",",$ids).") and regtime between '".$a."' and '".$b."' ";

 $tenderlist=M('admin');

 $list = $tenderlist->where($where)->select();

regtime 数据类型，timestamp ，例如：‘2017-2-15 9:31:32’.

不可以用时间戳对比查询，不起作用。

between "2017-3-1"  and "2017-3-15"  查询 timestamp 时间段的数据。