mongodb

开启服务端：mongod
开启客户端：mongo
新增数据：db.users.insert({userid:"admin",password:"123456"})
查找数据：db.users.find()
新增索引：1和-1表示升序和降序

> db.testnum.ensureIndex({"name":1});  
{  
        "createdCollectionAutomatically" : false,  
        "numIndexesBefore" : 1,  
        "numIndexesAfter" : 2,  
        "ok" : 1  
}  
>  
>  
> db.testnum.ensureIndex({"name":-1});  
{  
        "createdCollectionAutomatically" : false,  
        "numIndexesBefore" : 2,  
        "numIndexesAfter" : 3,  
        "ok" : 1  
}