Mongodb (II) simple summary of crud instructions

Time:2022-1-14

preface

This tutorial is suitable for those who have some experience in database development. For children’s shoes that are just beginning to contact the database, it is recommended to jump directly to the references of this article to choose a more suitable tutorial. Another thing to note is that there are great differences between version 2 and version 3 of mongodb. Be sure to pay attention when viewing the tutorial~

General instructions

use DATABASE_NAME: switch to the database. If the database does not exist, it will be created automatically
show dbs: view all databases
show tables: view all collections
db.dropDatabase(): delete the database after entering the database
db.COLLECTION_NAME.drop(): delete collection
db.COLLECTION_NAME.find(): view all or specific content in the collection

Insert document

db.COLLECTION_NAME.insertOne(): inserts a piece of document data into the specified collection
db.COLLECTION_NAME.insertMany(): inserts multiple document data into the specified collection

There are many equivalent insert operations

db.collection.update() : upsert:true
db.collection.updateOne(): upsert:true
db.collection.updateMany(): upsert:true
db.collection.findAndModify(): upsert:true
db.collection.findOneAndUpdate(): upsert:true
db.collection.findOneAndReplace(): upsert:true
db.collection.save().
db.collection.bulkWrite().

Update document

update

db.collection.update(
   <query>,
   <update>,
   {
     upsert: <boolean>,
     multi: <boolean>,
     writeConcern: <document>
   }
)

Query: query criteria of update, similar to the query criteria after where in SQL update query.
Update: update object and some Update Operators (such as $, $Inc…) And so on, which can also be understood as the data after the set in the SQL update query
Upsert: optional. This parameter means whether to insert objnew if there is no update record. True means insert. The default is false and not insert.
Multi: optional. Mongodb is false by default. Only the first record found will be updated. If this parameter is true, all the records found by conditions will be updated.
Writeconcern: optional, the level of exception thrown.

db.collection.updateOne()Updates a single document to the specified collection
db.collection.updateMany()Updates multiple documents to the specified collection
example:

db.COLLECTION_NAME.update(
    {'title':'mongodb tutorial '},
    {$set:{'title':'MongoDB'}},
    {multi:true}
)

save

    db.collection.save(
       <document>,
       {
         writeConcern: <document>
       }
    )

Document: document data.
Writeconcern: optional, the level of exception thrown.

replace

db.collection.replaceOne()

remove document

db.COLLECTION_NAME.deleteMany(): delete a single document
db.COLLECTION_NAME.deleteOne(): delete multiple documents

consult your documentation

db.COLLECTION_NAME.find({<field1>: <value1>, <field1>: { <operator1>: <value1> }}): field refers to the name and operator refers to the operator
db.collection.findOne()

example

db.inventory.find( { status: "D" } )
Equivalent toSELECT * FROM inventory WHERE status = "D"

db.inventory.find( { status: { $in: [ "A", "D" ] } } )
Equivalent toSELECT * FROM inventory WHERE status in ("A", "D")

db.inventory.find( { status: "A", qty: { $lt: 30 } } )
Equivalent toSELECT * FROM inventory WHERE status = "A" AND qty < 30

db.inventory.find( { $or: [ { status: "A" }, { qty: { $lt: 30 } } ] } )
Equivalent toSELECT * FROM inventory WHERE status = "A" OR qty < 30

More operator related viewsThis document

Query embedded objects using identifiers.

db.inventory.find( { "size.uom": "in" } )

References

Rookie tutorial getting started with mongodb
Runnob mongodb getting started
Mongodb Chinese Manual
Official course

Mongodb (II) simple summary of crud instructions
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