Nosql(MongoDB)

1)The following java script code is used to convert ObjectId to timestamp

//Get objectIds into one array

var objectIdArray=[ObjectId("5637162a2438eaba6ca1592c"),ObjectId("5590f5e6ff0b068aa08be97f")];

for (var i in objectIdArray){

printjson(objectIdArray[i].getTimestamp());

}

2)Execute java script file through command line and transfer output to text file

a) Execute javaScript file through command line

c:/>mongoDB/db/bin>mongo databaseName scriptName.js

ex:c:/>mongoDB/db/bin>mongo prod_hooperdb csvDataScript.js

b) Loading javaScript file output into text file

c:/>mongoDB/db/bin>mongo prod_hooperdb csvDataScript.js>csvData.txt

3)Unset multiple fields including array

db.day_schedule.update({"_id":ObjectId("5666a2f53a00a88de8923441"),"timeSlots.customerId": {$exists: true},
"timeSlots.serviceInstanceId": {$exists: true}},{$unset: {"timeSlots.$.customerId" : true,

    "timeSlots.$.serviceInstanceId":true } },false,true);

Unset single field

db.service_instance.update({},{$unset: {tags:1}},false,true)