use khdb
switched to db khdb
> db.desserts.insert({name: "salad", price: 15.50})
^[[A^[[A^[[A^[[AWriteResult({ "nInserted" : 1 })
> db.desserts.insert({name: "milkshake", price: 8.50, discount: 2})
WriteResult({ "nInserted" : 1 })
> db.desserts.insert({name: "cake", price: 6.50})
WriteResult({ "nInserted" : 1 })
> db.category.insert({name:"food"})
WriteResult({ "nInserted" : 1 })
> db.category.insert({name:"snack"})
WriteResult({ "nInserted" : 1 })
> db.category.insert({name:"sweet"})
WriteResult({ "nInserted" : 1 })
> db.category.insert({name:"fruit"})
WriteResult({ "nInserted" : 1 })
> db.products.insert({name:"bread", kcal: 70})
WriteResult({ "nInserted" : 1 })
> khdb.product.insert({name: "banana", price: 2.50})
2015-04-30T13:24:25.190+0200 E QUERY    ReferenceError: khdb is not defined
    at (shell):1:1
> db.products.insert({name:"crisps", kcal: 460})
WriteResult({ "nInserted" : 1 })
> db.products.insert({name:"chocolate", kcal: 511})
WriteResult({ "nInserted" : 1 })
> db.products.insert({name:"apple", kcal: 60})
WriteResult({ "nInserted" : 1 })
> db.desserts.update({$mul: {price: 0.95}})
2015-04-30T13:27:30.423+0200 E QUERY    Error: need an object
    at Error (<anonymous>)
    at DBCollection._parseUpdate (src/mongo/shell/collection.js:400:21)
    at DBCollection.update (src/mongo/shell/collection.js:432:23)
    at (shell):1:13 at src/mongo/shell/collection.js:400
> db.desserts.update({name: "salad"},{$mul: {price: 0.95}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.desserts.update({},{$mul: {price: 0.95}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.desserts.update({},{$mul: {price: 0.95}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.desserts.update({},{$mul: {price: 0.95}}, {multi:true})
WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })
> db.desserts.update({category:"fruit"},{$mul: {kcal: 0.95}}, {multi:true})
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
> db.products.update({category:"fruit"},{$mul: {kcal: 0.95}}, {multi:true})
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
> db.products.update({name: "bread"}, {$set: {category: "food"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.products.update({name: "apple"}, {$set: {category: "fruit"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.products.update({name: "banana"}, {$set: {category: "fruit"}})
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
> db.products.update({name: "chocolate"}, {$set: {category: "sweet"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.desserts.update({category:"fruit"},{$mul: {kcal: 0.95}}, {multi:true})
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
> db.products.update({name: "chocolate"}, {$set: {category: "sweet"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
> db.products.update({category:"fruit"},{$mul: {kcal: 0.95}}, {multi:true})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.products.insert({name:"banana", kcal: 130, category: "fruit"})
WriteResult({ "nInserted" : 1 })
> db.products.update({category:"fruit"},{$mul: {kcal: 1.1}}, {multi:true})
WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })
> db.products.count()
5
> db.desserts.count()
3
> db.products.update({category:"fruit"},{$set: {eko: 2}}, {multi:true})
WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })
> db.products.find({kcal:{$gte : 100}})
{ "_id" : ObjectId("554210f80cd6fe3ad7ecab72"), "name" : "crisps", "kcal" : 460 }
{ "_id" : ObjectId("5542110a0cd6fe3ad7ecab73"), "name" : "chocolate", "kcal" : 511, "category" : "sweet" }
{ "_id" : ObjectId("5542134e0cd6fe3ad7ecab75"), "name" : "banana", "kcal" : 143, "category" : "fruit", "eko" : 2 }
> db.products.find({kcal:{$gte : 100, category: "fruit"}})
Error: error: {
"$err" : "Can't canonicalize query: BadValue unknown operator: category",
"code" : 17287
}
> db.products.find({kcal:{$gte : 100}, category: "fruit"})
{ "_id" : ObjectId("5542134e0cd6fe3ad7ecab75"), "name" : "banana", "kcal" : 143, "category" : "fruit", "eko" : 2 }
> db.products.find({{$or: {kcal:{$gte : 100}, category: "fruit"}})
... ;
... ^C
> db.products.find({$or:[{kcal:{$gte : 100}, category: "fruit"}]})
{ "_id" : ObjectId("5542134e0cd6fe3ad7ecab75"), "name" : "banana", "kcal" : 143, "category" : "fruit", "eko" : 2 }
> db.products.find({$or:[{kcal:{$gte : 100}}, category: "fruit"]})
2015-04-30T13:40:38.006+0200 E QUERY    SyntaxError: Unexpected token :
> db.products.find({$or:[kcal:{$gte : 100}, category: "fruit"]})
2015-04-30T13:40:45.341+0200 E QUERY    SyntaxError: Unexpected token :
> db.products.find({$or:[{kcal:{$gte : 100}}, {category: "fruit"}]})
{ "_id" : ObjectId("554210f80cd6fe3ad7ecab72"), "name" : "crisps", "kcal" : 460 }
{ "_id" : ObjectId("5542110a0cd6fe3ad7ecab73"), "name" : "chocolate", "kcal" : 511, "category" : "sweet" }
{ "_id" : ObjectId("554211160cd6fe3ad7ecab74"), "name" : "apple", "kcal" : 62.7, "category" : "fruit", "eko" : 2 }
{ "_id" : ObjectId("5542134e0cd6fe3ad7ecab75"), "name" : "banana", "kcal" : 143, "category" : "fruit", "eko" : 2 }
> db.products.findOne({category:fruit})
2015-04-30T13:42:38.697+0200 E QUERY    ReferenceError: fruit is not defined
    at (shell):1:31
> db.products.findOne({category:"fruit"})
{
"_id" : ObjectId("554211160cd6fe3ad7ecab74"),
"name" : "apple",
"kcal" : 62.7,
"category" : "fruit",
"eko" : 2
}
> db.products.update({category:"fruit"},{$set: {tags: ["fruit", "diet", "eko"]}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.products.update({category:"fruit"},{$set: {tags: ["fruit", "diet", "eco"]}, {multi:true}})
2015-04-30T13:45:44.559+0200 E QUERY    SyntaxError: Unexpected token {
> db.products.update({category:"fruit"},{$set: {tags: ["fruit", "diet", "eco"]}, }, {multi:true})
WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })
> db.products.update({name:"apple"},{$set: {tags: ["fruit", "diet", "eco", "fibre"]}, }, {multi:true})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.products.find({$in:{tags: "fiber"}})
Error: error: {
"$err" : "Can't canonicalize query: BadValue unknown top level operator: $in",
"code" : 17287
}
> db.products.find({tags:{$in: "fiber"}})
Error: error: {
"$err" : "Can't canonicalize query: BadValue $in needs an array",
"code" : 17287
}
> db.products.find({tags:{$in: ["fiber]"}})
...
... db.products.find({tags:{$in: ["fiber]"}})
...
... ;
... db.products.find({tags:["fiber"]})
... db.products.find({ tags: ["fiber"]})
... db.products.find({tags:"fiber"})
... c^C
> show collections
category
desserts
products
system.indexes
> db.products.find({ tags: "fiber" })
> db.products.find({ tags: ["fiber]" })
... c^C
> db.products.find({ tags: ["fiber]" })
... ^C
> db.products.find({ tags: ["fiber"] })
> db.products.find({ tags: "eco" })
{ "_id" : ObjectId("554211160cd6fe3ad7ecab74"), "name" : "apple", "kcal" : 62.7, "category" : "fruit", "eko" : 2, "tags" : [ "fruit", "diet", "eco", "fibre" ] }
{ "_id" : ObjectId("5542134e0cd6fe3ad7ecab75"), "name" : "banana", "kcal" : 143, "category" : "fruit", "eko" : 2, "tags" : [ "fruit", "diet", "eco" ] }
> db.products.find({ tags: ["fibre"] })
> db.products.find({ tags: ["fibre"] })
> db.products.find({ tags: "fibre" })
{ "_id" : ObjectId("554211160cd6fe3ad7ecab74"), "name" : "apple", "kcal" : 62.7, "category" : "fruit", "eko" : 2, "tags" : [ "fruit", "diet", "eco", "fibre" ] }
> db.products.delete({category: "snacks"})
2015-04-30T13:53:37.614+0200 E QUERY    TypeError: Property 'delete' of object khdb.products is not a function
    at (shell):1:19
> db.products.remove({category: "snacks"})
WriteResult({ "nRemoved" : 0 })
> db.products.remove({category: "snack"})
WriteResult({ "nRemoved" : 0 })
> db.products.remove({category: "sweet"})
WriteResult({ "nRemoved" : 1 })
>