var mycursor = db.bar.find({_id:{$lte:5}})
 while(mycursor.hasNext()) {
  printjson(mycursor.next());
  }

 repSetTest:PRIMARY> db.version()
 3.0.12
 //创建包含29个文档的集合user
 repSetTest:PRIMARY> for (var i=1;i<30;i++){
 ... db.user.insert({"id":i,"ename":"usr"+i});
 ... }
 WriteResult({ "nInserted" : 1 })
 repSetTest:PRIMARY> db.user.count()
 29

 //查询集合user上所有文档
 repSetTest:PRIMARY> db.user.find()
 { "_id" : ObjectId("5804d07fd974b32430ea9748"), "id" : 1, "ename" : "usr1" }
 { "_id" : ObjectId("5804d07fd974b32430ea9749"), "id" : 2, "ename" : "usr2" }
 .............................
 { "_id" : ObjectId("5804d07fd974b32430ea975b"), "id" : 20, "ename" : "usr20" }
 Type "it" for more //上面的结果只输出了20行，这个提示表明查看更多应输入it

 repSetTest:PRIMARY> it
 { "_id" : ObjectId("5804d07fd974b32430ea975c"), "id" : 21, "ename" : "usr21" }
 ..............
 { "_id" : ObjectId("5804d07fd974b32430ea9764"), "id" : 29, "ename" : "usr29" }

 repSetTest:PRIMARY> var myCursor = db.user.find()
 while (myCursor.hasNext()) {
 print(tojson(myCursor.next()))
 }

 { "_id" : ObjectId("5804d07fd974b32430ea9748"), "id" : 1, "ename" : "usr1" }
 ..........
 {
 "_id" : ObjectId("5804d07fd974b32430ea9751"),
 "id" : 10,
 "ename" : "usr10"
 }
 ................
 {
 "_id" : ObjectId("5804d07fd974b32430ea9764"),
 "id" : 29,
 "ename" : "usr29"
 }
 //上述查询中通过var myCursor进行变量的定义，相当于SQL中的declare cursor cur_name is select ..
 //变量 myCursor定义仅仅是定义，并不会访问数据库，而是在myCursor.hasNext()真正访问数据库
 //myCursor.next()则是输出下一条记录，hasNext()访问数据库时会根据缺省游标设定将结果读取到本地

 repSetTest:PRIMARY> var myCursor = db.user.find({id:{$gt:20}})
 while (myCursor.hasNext()) {
 printjson(myCursor.next());}
 {
 "_id" : ObjectId("5804d07fd974b32430ea975c"),
 "id" : 21,
 "ename" : "usr21"
 }
 .......
 {
 "_id" : ObjectId("5804d07fd974b32430ea9764"),
 "id" : 29,
 "ename" : "usr29"
 }

 repSetTest:PRIMARY> var myCursor = db.user.find({id:{$gt:20}})
 repSetTest:PRIMARY> myCursor.forEach(printjson);
 {
 "_id" : ObjectId("5804d07fd974b32430ea975c"),
 "id" : 21,
 "ename" : "usr21"
 }
 ................
 {
 "_id" : ObjectId("5804d07fd974b32430ea9764"),
 "id" : 29,
 "ename" : "usr29"
 }

 //如下示例，将游标返回的内容传递到数组，然后使用 printjson (documentArray[3])输出其中的元素
 repSetTest:PRIMARY> var myCursor = db.user.find({id:{$gt:20}})
 repSetTest:PRIMARY> var documentArray = myCursor.toArray();
 repSetTest:PRIMARY> printjson (documentArray[3])
 {
 "_id" : ObjectId("580d775edeb57e4d05eec0f2"),
 "id" : 24, //Author : Leshami
 "ename" : "usr24" //Blog : http://blog.csdn.net/leshami
 }

 //也可以将数组元素输出到某个变量，然后在用printjson(myDocument)输出这个变量，如下
 repSetTest:PRIMARY> var myDocument = documentArray[3];
 repSetTest:PRIMARY> printjson(myDocument)
 {
 "_id" : ObjectId("580d775edeb57e4d05eec0f2"),
 "id" : 24,
 "ename" : "usr24"
 }

 //设置迭代显示的次数，如下设置为5
 repSetTest:PRIMARY> DBQuery.shellBatchSize = 5
 5
 repSetTest:PRIMARY> db.user.find()
 { "_id" : ObjectId("5804d07fd974b32430ea9748"), "id" : 1, "ename" : "usr1" }
 { "_id" : ObjectId("5804d07fd974b32430ea9749"), "id" : 2, "ename" : "usr2" }
 { "_id" : ObjectId("5804d07fd974b32430ea974a"), "id" : 3, "ename" : "usr3" }
 { "_id" : ObjectId("5804d07fd974b32430ea974b"), "id" : 4, "ename" : "usr4" }
 { "_id" : ObjectId("5804d07fd974b32430ea974c"), "id" : 5, "ename" : "usr5" }
 Type "it" for more //从上面的查询结果可知，当输出5个文档就提示需要输入it来查看更多
 repSetTest:PRIMARY> it
 { "_id" : ObjectId("5804d07fd974b32430ea974d"), "id" : 6, "ename" : "usr6" }
 { "_id" : ObjectId("5804d07fd974b32430ea974e"), "id" : 7, "ename" : "usr7" }
 { "_id" : ObjectId("5804d07fd974b32430ea974f"), "id" : 8, "ename" : "usr8" }
 { "_id" : ObjectId("5804d07fd974b32430ea9750"), "id" : 9, "ename" : "usr9" }
 { "_id" : ObjectId("5804d07fd974b32430ea9751"), "id" : 10, "ename" : "usr10" }
 Type "it" for more

 //如下查询本机游标的信息 
 repSetTest:PRIMARY> db.serverStatus().metrics.cursor
 {
 "timedOut" : NumberLong(2),
 "open" : {
  "noTimeout" : NumberLong(0),
  "pinned" : NumberLong(0),
  "total" : NumberLong(2)
 }
 }