MongoDB data Query

Start MongoDB: sudo service mongodb start ,mongo

• After testing, the key can be quoted or not added, but the value is generally quoted, except for the value type
• MongoDB is case-sensitive, and naming is usually based on the camel-named method
• MongoDB will be created automatically if the database/collection does not exist in the case of using database, inserting collection, etc.

Data query find()

• db.<集合名>.find({<键名>:<值>,...})
• Formatting result sets: Post-add .pretty()db.<CollectionName>.find({key:‘value‘,...}).pretty()
• MongoDB in theAND
  When find() multiple key-value pairs are passed in, MongoDB handles them as an and. e.g.:db.collection.find({name:‘123‘,age:{$gt:20}})
• MongoDB in theOR
  Use $or as a keyword, e.g.:db.collection.find({$or:[{key1:‘value1‘},{key2:‘value2‘}]})
• {$gt:20}Represents greater than 20, in addition, less than, less than or equal $lt $lte to, $gte greater than or equal to, $ne not equal to

MongoDB data Query