php实现Mongodb自定义方式生成自增ID的方法

//首先创建一个自动增长id集合 ids
>db.ids.save({name:"user",id:0});
//可以查看一下是否成功
> db.ids.find();
{ "_id" : ObjectId("4c637dbd900f00000000686c"),"name" : "user","id" : 0 }
//然后每次添加新用户之前自增一下 ids集合 获得id
>userid = db.ids.findAndModify({update:{$inc:{'id':1}},query:{"name":"user"},new:true});
{ "_id" : ObjectId("4c637dbd900f00000000686c"),"id" : 1 }
//注：因为findAndModify是一个办法完成更新查找两个操作,所以具有原子性,多线程不会冲突.
//然后保存相应的数据
>db.user.save({uid:userid.id,username:"kekeles",password:"kekeles",info:"/ "});
//查看结果
> db.user.find();
{ "_id" : ObjectId("4c637f79900f00000000686d"),"uid" : 1,"username" : "admin","password" : "admin" }
//这是mongo的shell,如果用的是服务器端程序java php python,可以自己对这些操作封装一下,只用传几个参数就可以返回自增的id,还可以实现像Oracle的跨表的自增id.

<?php
function mid($name,$db){
$update = array('$inc'=>array("id"=>1));
$query = array('name'=>$name);
$command = array(
'findandmodify'=>'ids','update'=>$update,'query'=>$query,'new'=>true,'upsert'=>true
);
$id = $db->command($command);
return $id['value']['id'];
}
$conn = new Mongo();
$db = $conn->idtest;
$id = mid('user',$db);
$db->user->save(array(
'uid'=>$id,'username'=>'kekeles','password'=>'kekeles','info'=>'/ '
));
$conn->close();
?>