Add delete change and search orders

1 List and select

1.1 List all databases

> show dbs 
local  0.000GB
myblog 0.000GB

1.2 Use a database

> use myblog
switched to db myblog

1.3 List all collections

> show collections
articles
replicationColletion
sessions
users
wangduanduan

2 Insert data insert(value)

//  Inserts data into an existing collection 
> db.users.insert({name:'hh',age:23})
Inserted 1 record(s) in 43ms

//  Inserts data into a collection that does not exist , The collection is automatically created and inserted when it does not exist 
> db.students.insert({name:'hh',age:23})
Inserted 1 record(s) in 72ms

Three query find (option)

3.1 Query all documents in the collection

> db.users.find()
/* 1 */
{
  "_id" : ObjectId("583e908453be942d0c5419dc"),
  "login_name" : "wangduanduan",
  "password" : "wrong age"
}

/* 2 */
{
  "_id" : ObjectId("583ed2a5cc9a937db049616d"),
  "login_name" : "hh",
  "password" : "sdfsdf"
}

/* 3 */
{
  "_id" : ObjectId("583fb2e9b12f8b7a7aa37572"),
  "name" : "wangduanduan",
  "age" : 34.0
}

/* 4 */
{
  "_id" : ObjectId("583fb707b12f8b7a7aa37573"),
  "name" : "hh",
  "age" : 23.0
}

3.2 Query documents by conditions

> db.users.find({name:'wangduanduan'})
/* 1 */
{
  "_id" : ObjectId("583fb2e9b12f8b7a7aa37572"),
  "name" : "wangduanduan",
  "age" : 34.0
}

Pay attention to

//  That's wrong. I can't find the results 
> db.users.find({_id:'583fb2e9b12f8b7a7aa37572'})
Fetched 0 record(s) in 1ms

//  This is correct 
> db.users.find({_id:ObjectId('583fb2e9b12f8b7a7aa37572')})
/* 1 */
{
  "_id" : ObjectId("583fb2e9b12f8b7a7aa37572"),
  "name" : "wangduanduan",
  "age" : 34.0
}

3.3 Number of documents in the query collection

> db.users.count()
4

3.4 Comparison operators

$gt: greater than

$gte: greater than or equal to

$lt: less than

$lte: less than or equal to

$ne: is not equal to

//  The query user is older than 30 The age of,   And so on 
> db.user.find({age:{$gt:30}})

/* 1 */
{
  "_id" : ObjectId("583fb2e9b12f8b7a7aa37572"),
  "name" : "wangduanduan",
  "age" : 34.0
}

3.5 Logical operators

3.5.1 track of and

> use myblog
switched to db myblog

0

3.5.2 $in or

> use myblog
switched to db myblog

1

3.5.3 $nin non

> use myblog
switched to db myblog

2

3.6 Regular matching

//  The query name is contained in duan The user 
> db.users.find({name:/duan/})
/* 1 */
{
  "_id" : ObjectId("583fb2e9b12f8b7a7aa37572"),
  "name" : "wangduanduan",
  "age" : 34.0
}

/* 2 */
{
  "_id" : ObjectId("583fc919b12f8b7a7aa37575"),
  "name" : "wangduanduan",
  "age" : 45.0
}

3.7 big recruit $where

> use myblog
switched to db myblog

4

4 update update ();

4.1 Overall Update

> db.users.update({login_name:'wangduanduan'},{name:'heihei',age:34})
Updated 1 existing record(s) in 116ms

4.2 $set partial update

// Just set the user age to 101
> db.users.update({name:'wangduanduan'},{$set:{age:101}})


4.3 $inc

// Increase the user's age by 1 year, if the document does not have the age field
> db.users.update({name:'wangduanduan'},{$inc:{age:1}})


4.3 upsert operation

// If the document cannot be found, add the document
> db.users.update({name:'nobody'},{$inc:{age:1}},true)
Updated 1 new record(s) in 3ms

/* 6 */
{
"_id" : ObjectId("583fd20f2cfa6a4817c4171c"),
"name" : "nobody",
"age" : 1.0
}

4.4 Batch update

When the fourth parameter of upadate is set to true, it will be updated in batches
> db.users.update({name:'wangduanduan'},{$set:{age:1891}},false,true)


5 to delete

// Delete some documents
db.person.remove({"name":"joe"})

// Delete the entire collection
db.person.remove()