1. Insert the document
1. db.collection name.insert()
Insert one: db.user.insert({name: "Join", age: 13, address: "beijing", isDelete: 0})
插入多个：db.user.insert([{name："Join",age：13，address："beijing",isDelete:0},{name："Join2",age：13，address："beijing",isDelete:0},{name："Join3",age：13，address："beijing",isDelete:0}])
2. db.collection name.save()
Specify _id to modify and update: db.user.save({_id:ObjectId("234567892345678"),name:"Join",age:13,address:"beijing",isDelete:0})
If _id is not specified, it is the same as insert, which is new: db.user.save({name: "Join4", age: 13, address: "beijing", isDelete: 0})
2. Document update
1. Update an existing document: db.collection name.update()
db.集合名.update（<query>,<update>,{upset:<boolean>,multi:<boolean>,writeConcern:<document>}）
query: query condition
update operator: $set----update immediately; $inc----update after accumulative increase on the original basis
multi: optional, the default is false, if true, only the first item will be updated
writeConcert: optional, the level of exception thrown
eg：db.user.update({name:"Join"},{$set:{age:21}})
2. Replace the existing document by passing in the document, db.collection name.save()
db.collectionname.save(document data, {writeConcern:<document>})
3. Document deletion
db.collectionname.remove()
db.集合名.remove(<query>,{justOne:<boolean>,writeConcern:<document>})
4. Document query
1. Query all documents in the collection: db.collection name.find()
2. Query the documents that meet the requirements: db.collection name.find(<query>,{<key>:1,<key>:2...}), query is the requirement for judging the query, and key is the query displayed What content 1 is displayed
eg:db.user.find({age:21}，{age:1,name:1})
3. Display in a formatted way: pretty()
eg：db.user.find().pretty()
4. After the query, display the first content that matches the result: findOne()
5. Query condition operator
| content | conform to | expression |
| more than the | $gt | db.collectionname.({<key>:{$gt:<value>}}) |
| greater or equal to | $gte | db.collectionname.({<key>:{$gte:<value>}}) |
| less than | $lt | db.collectionname.({<key>:{$lt:<value>}}) |
| less than or equal to | $lte | db.collectionname.({<key>:{$lte:<value>}}) |
| equal | : | db.collectionname.({<key>:<value>}) |
| not equal to | $ne | db.collectionname.({<key>:{$ne:<value>}}) |
| query using _id | _id | db.collection name.({"_id":ObjectId("id value")}) |
| Number of matching results | count | db.集合名.({<key>:<value>}).count() |
| Whether a field in the query result contains a certain value | /contained value/ | db.collectionname.({name:/io/}) |
| Whether a field in the query result starts with a value | /^ contains the value/ | db.collection name.({name:/^J/}) |
6. Conditional query and, or
and:db.集合名.find({<key>:<value>,<key2>:<value2>,<key3>:<value3>})
or :db.集合名.find({$or:[{<key>:<value>},{<key2>:<value2>}]})
7、limit、skip
limit(): Read the specified amount of data content
eg: db.collection name.find().limit(5) Read the first 5 pieces of data
skip(): skip the specified amount of data content
eg: db.collection name.find().skip(5) skip the first 5 data
8. Sort
db.setname.find().sort({key:1})
1 for ascending order, -1 for descending order