How mongodb inserts, deletes and updates documents

MongoDB What's wrong Document Insert 、 Delete and update

This article mainly introduces MongoDB What's wrong Document Insert 、 Delete and update relevant knowledge , The content is detailed and easy to understand , The operation is simple and fast , It has certain reference value , I believe that after reading this article MongoDB What's wrong Document Insert 、 Deleting and updating articles will be beneficial , Let's have a look .

One .Document Insert data into

1. Inserted into the document

db.[ Document name ].insert({BSON data })

2. Batch insert documents

shell Batch insertion is not supported , Want to complete the batch insert operation , have access to shell Of for loop , Or the batch operation method in other high-level languages

example ： Use for Circular insert 10 A student , Among the students

I'm using 2.6 Version of , It is found that batch insert operation has been supported .

3.Save operation

save Operation and insert The difference in operation is ,save In case of _id When the same data is inserted , Will cover the original , and insert It will give you an error

Example ：

use insert To insert a _id Same data

Two .Document Data deletion

1. Delete all data in the list

db.[ Document name ].remove({})

The collection itself and index will not be deleted

Example : Delete all data in the list

2. Delete... According to conditions

example : Delete _id by 10 The record of

3、 ... and .Document Data update

1. Direct coverage update

db.[ Document name ].update({ Inquire device },{ Modifier })

{ Inquire device } It's equivalent to the condition

{ Modifier } That's what you want to replace directly BSON data

example ： to update _id by 9, The student , hold Name become age

Be careful ： When the primary key conflicts, an error will be reported and the update operation will be stopped

example ： I use _id by 8 The data of , Replace _id by 9 The record of , because _id by 8 The data already exists , Two primary keys are not allowed to be _id:8

The record of , So there's an error .

2. use insertOrUpdate To update

db.[ Document name ].update({ Inquire device },{ Modifier },true)

The next third parameter is true, It means when the record doesn't exist , Just insert a record , Update if it exists

example ： Update one _id by 10 The data of , Insert without , Update if you have

3. Batch update operation

db.[ Document name ].update({ Inquire device },{ Modifier },false, true)

※ By default, the first data will be modified by default when the query finds multiple data

First modify the data as follows :

Give Way _id by 9 and 10 The data of , There's the same thing

Insert one more _id=11,age=20 The data of

The fourth parameter is updated without writing ：

as follows ： Only the first age=20 The data of

The fourth parameter is added and is true When , Our expectation is 10 and 11 Can be fixed

But when I try to update , Wrong report , The prompt says that batch update can only be done when ＄ Use when operating

Fixed insert statement

Note here $set There's going to be ":", And it and the modifiers behind it will be {} wrap up , Because I used it for the first time mongoDB, So it's always wrong .

4. Use the modifier to complete the local update operation

$set It is used to specify a key value pair , If there is a key, modify it. If there is no key, add it

{$set:{field:value}}

_id by 10 The data of , No, Name attribute , Added , Yes age key , It was modified

$inc

1. For number types

2. It can add and subtract the number type value corresponding to the key

{$inc:{field:value}}

to age=30 The data of 2 year , Since batch update parameters are not used , So the first one was amended by default

$unset Delete specified key

{$unset:{field:1}}

In the example, I deleted age=30 Data. age attribute , But one thing I don't understand ,unset Behind the field：1 What is it? , So I checked , It doesn't matter what's behind it ,unset Just look at the key, not value, So I made a second example

$push

1. If the specified key is an array increment, append a new value

2. If the specified key is not an array, the current operation is interrupted , Report errors

3. If the specified key does not exist, create a key value pair of array type

{$push:{field:value}}

$pushAll

Same as above , Is the operation of batch adding array data

{$pushAll:{field:array}}

1. The first operation doesn't work $pushAll, So the ["C#","JAVA"] Treated as an array item

2. The second operation uses $pushAll, So it's treated as two items .

$addToSet

Add items to the array , There is no need to add , Add... If it doesn't exist （push Add it whether it exists or not ）

{$addToSet:{field:value}}

1. First use push Insert , I found that after the update, there are two “C#”

2. Reuse addToSet to update , Found no additional items

$pop

Removes a value from the specified array 1 Delete the last value ,-1 Delete the first value

{$pop:{field:value}}

1. Delete data from the last index position , hinder value use "1"

2. Delete the data of the first position index ,value=-1

$pull

push Reverse operation , The delete key is the specified element in the item of the array

{$pull:{field:value}}

$pullAll

Batch delete the specified elements in the array

{$pullAll:{field:array}}

$ Array locators , If the array has multiple values, we only want to operate on some of them, we need to use locators ($)

{$push:{field:value}}

1. The first example is to add two elements to the array just cleared

2. I want to {“SubID”:1,"SubName":"MangoDB"} Add... To this object "Teacher":"Lucy"

5.$addToSet And $each Combined with the completion of batch array update

understand : First of all, from the example above, we know that ,addToSet This modifier , You can judge whether the project exists , Insert it when it doesn't exist .

Now I have a function , For example, I want to batch update data in an array with data , If it exists, it will not be updated . So just use addToSet You can't do it in batches , So we have to combine $each To achieve .

example ：

1. Create a new file , And use pushAll Modifier to add data :

2. I want to batch insert "C#","PHP","JavaScript","JAVA", There should be no repetition of the requirements

If I use it right now pushAll To update ,"C#" and "JAVA" There will be repetition

stay shell Enter the following command ：

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