mongodb-lectures/02.MONGO_UPDATE.md

Mongo - Update

Lesson Objectives

1. Explain how to replace a record
2. Explain how to update certain values for a record
3. Explain update operators
4. Explain upserts
5. Explain multiple updates

Explain how to replace a record

1.db.employees.update({name:'Roooooodles'}, {weight: 590})

Explain how to update certain values for a record

db.employees.update(
	{weight: 590},
	{$set: {
		name: 'Roooooodles',
		dob: new Date(1979, 7, 18, 18, 44),
		loves: ['apple'],
		gender: 'm',
		salary: 99}})

Explain update operators

1. db.employees.update({name: 'Pilot'}, {$inc: {salary: -2}})
2. db.employees.update({name: 'Pilot'}, {$mul: {salary: (1/2)}})
3. db.employees.update({name: 'Aurora'}, {$push: {loves: 'sugar'}})
4. db.employees.update({name: 'Aurora'}, {$pop: 1})
5. db.employees.update({name: 'Aurora'}, {$unset: {loves: ''}})
6. db.employees.update({name: 'Aurora'}, {$rename: {wrong_field_name : 'correct_field_name'}})
7. http://docs.mongodb.org/manual/reference/operator/update/#update-operators

Explain multiple updates

1. update() updates first entry

db.employees.update(
	{},
	{$set: {vaccinated: true}},
	{multi:true});
db.employees.find({vaccinated: true});

Explain upserts

1. db.hits.update({page: 'employees'}, {$inc: {hits: 1}}); db.hits.find();
2. db.hits.update({page: 'employees'}, {$inc: {hits: 1}}, {upsert:true}); db.hits.find();