mongodb数据库实验之增删查改

db.user.insert(
 {
  _id: 2018211,
  user_id: 201821057900000000000000000000000,
  name: "xiao",
  review_count: 100,
  "yelping_since": ISODate("2020-11-17 07:58:51"),
 }
)

db.user.insertMany(
 [ {
  _id: 201821112,
  user_id: 201811111111111111111111,
  name: "xiaoxiao",
  review_count: 1,
  "yelping_since": ISODate("2020-11-18 07:58:51"),
 },
   {
  _id: 201821114,
  user_id: 201822222222222222222,
  name: "xuexiao",
  review_count: 344,
  "yelping_since": ISODate("2030-11-18 07:58:51"),
 },
   {
  _id: 201821117,
  user_id: 201833333333333333333,
  name: "xiaoxiao",
  review_count: 56,
  "yelping_since": ISODate("2020-11-19 07:58:51"),
 },]
  
)

db.business.remove({
 "city": "Las Vegas",
 stars: {
  $lt:3
 }
})

db.user.update({_id: 2018211125},

 {name:"xiaoxiao", review_count: 0,yelping_since: ISODate("2020-11-18 21:58:51")})

db.business.update({business_id:8mIrX_LrOnAqWsB5JrOojQ},
{ "$inc":{stars:0.5}
}
)

db.business.find({
 latitude: {
  "$gte": 30,
  "$lte": 50
 },
 state: "AZ"
}).limit(10)

db.business.find({
 city: {
  "$in": ["Charlotte", "Toronto", "cottsdale"]
 }
}).skip(150)

db.friend.createIndex({user_id:1 ,friend_id: -1})

db.friend.getIndexes()

db.review.aggregate([
 {
  $match: {
    "stars": {
   "$gte": 2.0
   }
  }
 },
 {
  $group: {
   _id: "$user_id",
  starSum:{
    $sum: "$stars"
   }
  }
 },
 
])

db.friend.aggregate([
 {
  $match: {
   friend_id:"BI4jBJVto2tEQ0NiaR0rNQ"
  }
 },
 {
  $group: {
   _id: "$friend_id",
  Sum:{
    $sum: "$count",
   }
  }
 },
 
]).skip(10)

db.friend.distinct(
 "friend_id"
 )