一、Find查询

事前准备：插入如下数据

db.Students.insert([
{ _id:1, name:”Zhao”, age:25, country:”USA”, books:[“JS”,”C++”,”EXTJS”,”MONGODB”]},
{ _id:2, name:”Qian”,age:22, country:”USA”, books:[“PHP”,”JAVA”,”EXTJS”,”C++”]},
{ _id:3,name:”Sun”,age:26, country:”USA”, books:[“JS”,”JAVA”,”C#”,”MONGODB”]},
{ _id:4, name:”Li”,age:27,country:”China”,books:[“JS”,”JAVA”,”EXTJS”,”MONGODB”]},
{ _id:5,name:”Zhou”, age:30,country:”China”,books:[“JS”,”C#”,”PHP”,”MONGODB”]},
{ _id:6, name:”Wu”, age:27, country:”Japan”, books:[“JS”,”JAVA”,”C++”,”MONGODB”]},
{ _id:7, name:”Zheng”, age:27, country:”UK”, books:[“JS”,”JAVA”,”EXTJS”,”PHP”]},
{ _id:8, name:”Wang”, age:26, country:”Korea”,books:[“JS”,”C#”,”EXTJS”,”MONGODB”]}
])