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# Mongo - Update
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## Lesson Objectives
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1. Explain how to replace a record
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1. Explain how to update certain values for a record
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1. Explain update operators
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1. Explain upserts
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1. Explain multiple updates
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## Explain how to replace a record
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1.`db.employees.update({name:'Roooooodles'}, {weight: 590})`
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## Explain how to update certain values for a record
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```
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db.employees.update(
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{weight: 590},
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{$set: {
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name: 'Roooooodles',
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dob: new Date(1979, 7, 18, 18, 44),
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loves: ['apple'],
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gender: 'm',
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salary: 99}})
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```
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## Explain update operators
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1. `db.employees.update({name: 'Pilot'}, {$inc: {salary: -2}})`
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1. `db.employees.update({name: 'Pilot'}, {$mul: {salary: (1/2)}})`
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1. `db.employees.update({name: 'Aurora'}, {$push: {loves: 'sugar'}})`
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1. `db.employees.update({name: 'Aurora'}, {$pop: 1})`
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1. `db.employees.update({name: 'Aurora'}, {$unset: {loves: ''}})`
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1. `db.employees.update({name: 'Aurora'}, {$rename: {wrong_field_name : 'correct_field_name'}})`
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1. http://docs.mongodb.org/manual/reference/operator/update/#update-operators
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## Explain multiple updates
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1. update() updates first entry
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```
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db.employees.update(
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{},
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{$set: {vaccinated: true}},
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{multi:true});
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db.employees.find({vaccinated: true});
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```
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## Explain upserts
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1. `db.hits.update({page: 'employees'}, {$inc: {hits: 1}}); db.hits.find();`
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1. `db.hits.update({page: 'employees'}, {$inc: {hits: 1}}, {upsert:true}); db.hits.find();`
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