$tmp_uids=array_chunk($uids,900);

$diabetes_project=new Tdiabetes_project();

$whereStr='';

foreach ($tmp_uids as $k=>$v){

    $whereStr.= " id in ('".implodeFor8("','",$v)."') or";

}

$whereStr=rtrim($whereStr,'or');

$diabetes_project->whereAdd($whereStr);

array_chunk可以按length对数组进行拆分。