Question

描述

本教程我们将向大家介绍如何在 MongoDB 集合中获取数据。

我们使用的数据库名称为"myinfo" 我们的集合名称为"userdetails"，以下为我们插入的数据：

> db.userdetails.insert({"user_id" : "user1","password" :"1a2b3c" ,"date_of_join" : "16/10/2010" ,"education" :"M.C.A."  
, "profession" : "CONSULTANT","interest" : "MUSIC","community_name" :["MODERN MUSIC", "CLASSICAL MUSIC","WESTERN  
MUSIC"],"community_moder_id" : ["MR. Alex","MR. Dang","MR Haris"],"community_members" :  
[700,200,1500],"friends_id" : ["kumar","harry","anand"],"ban_friends_id" :["Amir","Raja","mont"]});

> db.userdetails.insert({"user_id" : "user2","password" :"11aa1a" ,"date_of_join" : "17/10/2009" ,"education"  
:"M.B.A." , "profession" : "MARKETING","interest" : "MUSIC","community_name" :["MODERN MUSIC", "CLASSICAL  
MUSIC","WESTERN MUSIC"],"community_moder_id" : ["MR. Roy","MR. Das","MR Doglus"],"community_members" :  
[500,300,1400],"friends_id" : ["pal","viki","john"],"ban_friends_id" :["jalan","monoj","evan"]});

> db.userdetails.insert({"user_id" : "user3","password" :"b1c1d1" ,"date_of_join" : "16/10/2010" ,"education"  
:"M.C.A." , "profession" : "IT COR.","interest" : "ART","community_name" :["MODERN ART", "CLASSICAL ART","WESTERN  
ART"],"community_moder_id" : ["MR. Rifel","MR. Sarma","MR Bhatia"],"community_members" :  
[5000,2000,1500],"friends_id" : ["philip","anant","alan"],"ban_friends_id" :["Amir","Raja","mont"]});

> db.userdetails.insert({"user_id" : "user4","password" :"abczyx" ,"date_of_join" : "17/8/2009" ,"education"  
:"M.B.B.S." , "profession" : "DOCTOR","interest" : "SPORTS","community_name" :["ATHELATIC", "GAMES FAN  
GYES","FAVOURIT GAMES"],"community_moder_id" : ["MR. Paul","MR. Das","MR Doglus"],"community_members" :  
[2500,2200,3500],"friends_id" : ["vinod","viki","john"],"ban_friends_id" :["jalan","monoj","evan"]});

从集合中获取数据

如果你想在集合中读取所有的的数据，可以执行以下命令

> db.userdetails.find();

类似于如下 SQL 查询语句：

Select * from userdetails;

输出数据如下所示：

通过指定条件读取数据

如果我们想在集合"userdetails"中读取"education"为"M.C.A." 的数据，我们可以执行以下命令：

> db.userdetails.find({"education":"M.C.A."})

类似如下 SQL 查询语句:

Select * from userdetails where education="M.C.A.";

输出结果如下所示：