# Mongo - Update

## Lesson Objectives
1. Explain how to replace a record
1. Explain how to update certain values for a record
1. Explain update operators
1. Explain upserts
1. 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'}, {$inc: {salary: -2}})`
1. `db.employees.update({name: 'Pilot'}, {$mul: {salary: (1/2)}})`
1. `db.employees.update({name: 'Aurora'}, {$push: {loves: 'sugar'}})`
1. `db.employees.update({name: 'Aurora'}, {$pop: 1})`
1. `db.employees.update({name: 'Aurora'}, {$unset: {loves: ''}})`
1. `db.employees.update({name: 'Aurora'}, {$rename: {wrong_field_name : 'correct_field_name'}})`
1. 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'}, {$inc: {hits: 1}}); db.hits.find();`
1. `db.hits.update({page: 'employees'}, {$inc: {hits: 1}}, {upsert:true}); db.hits.find();`