> show dbs;
admin   0.000GB
config  0.000GB
local   0.000GB
> db.collection('emp').insertOne("{'empId':'1001','empName':'Scott'}");
2019-04-16T17:09:05.816+0530 E QUERY    [js] TypeError: db.collection is not a function :
@(shell):1:1
> db.emp.insertOne({'empId':'1001','empName':'Scott'});
{
        "acknowledged" : true,
        "insertedId" : ObjectId("5cb5bf8144cce71ac6ae2444")
}
> db.emp.insertOne({'empId':'1002','empName':'Jack'});
{
        "acknowledged" : true,
        "insertedId" : ObjectId("5cb5bf8e44cce71ac6ae2445")
}
> show dbs;
admin   0.000GB
config  0.000GB
emp_db  0.000GB
local   0.000GB
> show collections;
emp
> use local
switched to db local
> show collections;
startup_log
> use emp_db;
switched to db emp_db
> show collections;
emp
> db.emp.find();
{ "_id" : ObjectId("5cb5bf8144cce71ac6ae2444"), "empId" : "1001", "empName" : "Scott" }
{ "_id" : ObjectId("5cb5bf8e44cce71ac6ae2445"), "empId" : "1002", "empName" : "Jack" }
> db.emp.insertOne({'empName':'Ram','project':'LKM'});
{
        "acknowledged" : true,
        "insertedId" : ObjectId("5cb5c12444cce71ac6ae2446")
}
> db.emp.find();
{ "_id" : ObjectId("5cb5bf8144cce71ac6ae2444"), "empId" : "1001", "empName" : "Scott" }
{ "_id" : ObjectId("5cb5bf8e44cce71ac6ae2445"), "empId" : "1002", "empName" : "Jack" }
{ "_id" : ObjectId("5cb5c12444cce71ac6ae2446"), "empName" : "Ram", "project" : "LKM" }
> db.emp.find(
... {"empName":"Ram"}
... )
{ "_id" : ObjectId("5cb5c12444cce71ac6ae2446"), "empName" : "Ram", "project" : "LKM" }
> db.emp.update(
... {empName: "Ram},
2019-04-16T17:23:36.856+0530 E QUERY    [js] SyntaxError: unterminated string literal @(shell):2:10
> db.emp.update( {empName:"Ram},
2019-04-16T17:23:55.392+0530 E QUERY    [js] SyntaxError: unterminated string literal @(shell):1:24
> db.emp.update({empName: "Ram},
2019-04-16T17:24:20.321+0530 E QUERY    [js] SyntaxError: unterminated string literal @(shell):1:24
> db.emp.update(
... {name : "Ram"},
... {$set: {empId:"1003"}}
... );
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
> db.emp.update( {empName : "Ram"}, {$set: {empId:"1003"}} );
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.emp.find();
{ "_id" : ObjectId("5cb5bf8144cce71ac6ae2444"), "empId" : "1001", "empName" : "Scott" }
{ "_id" : ObjectId("5cb5bf8e44cce71ac6ae2445"), "empId" : "1002", "empName" : "Jack" }
{ "_id" : ObjectId("5cb5c12444cce71ac6ae2446"), "empName" : "Ram", "project" : "LKM", "empId" : "1003" }
> db.emp.updateMany(
... {$set:{age:25}}
... );
2019-04-16T17:27:27.882+0530 E QUERY    [js] TypeError: can't convert undefined to object :
DBCollection.prototype.updateMany@src/mongo/shell/crud_api.js:618:16
@(shell):1:1
> db.emp.updateMany( {$set:{age:'25'}} );
2019-04-16T17:27:40.154+0530 E QUERY    [js] TypeError: can't convert undefined to object :
DBCollection.prototype.updateMany@src/mongo/shell/crud_api.js:618:16
@(shell):1:1
> db.emp.updateMany( {$set:{age:"25"}} );
2019-04-16T17:28:15.195+0530 E QUERY    [js] TypeError: can't convert undefined to object :
DBCollection.prototype.updateMany@src/mongo/shell/crud_api.js:618:16
@(shell):1:1
> db.emp.updateMany({},{$set:{age:"25"}} );
{ "acknowledged" : true, "matchedCount" : 3, "modifiedCount" : 3 }
> db.emp.find();
{ "_id" : ObjectId("5cb5bf8144cce71ac6ae2444"), "empId" : "1001", "empName" : "Scott", "age" : "25" }
{ "_id" : ObjectId("5cb5bf8e44cce71ac6ae2445"), "empId" : "1002", "empName" : "Jack", "age" : "25" }
{ "_id" : ObjectId("5cb5c12444cce71ac6ae2446"), "empName" : "Ram", "project" : "LKM", "empId" : "1003", "age" : "25" }
> db.emp.update( {empName : "Ram"}, {$set: {age:"35"}} );
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.emp.find();
{ "_id" : ObjectId("5cb5bf8144cce71ac6ae2444"), "empId" : "1001", "empName" : "Scott", "age" : "25" }
{ "_id" : ObjectId("5cb5bf8e44cce71ac6ae2445"), "empId" : "1002", "empName" : "Jack", "age" : "25" }
{ "_id" : ObjectId("5cb5c12444cce71ac6ae2446"), "empName" : "Ram", "project" : "LKM", "empId" : "1003", "age" : "35" }
> db.emp.update(
... {age: { $lt: 30 }},
... {$set:{project:"Fresher"}}
... );
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
> db.emp.update( {age: { $lt: "30" }}, {$set:{project:"Fresher"}} );
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.emp.find();
{ "_id" : ObjectId("5cb5bf8144cce71ac6ae2444"), "empId" : "1001", "empName" : "Scott", "age" : "25", "project" : "Fresher" }
{ "_id" : ObjectId("5cb5bf8e44cce71ac6ae2445"), "empId" : "1002", "empName" : "Jack", "age" : "25" }
{ "_id" : ObjectId("5cb5c12444cce71ac6ae2446"), "empName" : "Ram", "project" : "LKM", "empId" : "1003", "age" : "35" }
> db.emp.deleteOne(
... {project:"Fresher"}
... );
{ "acknowledged" : true, "deletedCount" : 1 }
> db.emp.find();
{ "_id" : ObjectId("5cb5bf8e44cce71ac6ae2445"), "empId" : "1002", "empName" : "Jack", "age" : "25" }
{ "_id" : ObjectId("5cb5c12444cce71ac6ae2446"), "empName" : "Ram", "project" : "LKM", "empId" : "1003", "age" : "35" }