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This article mainly explains the basic operation of summarizing MongoDB database, the content is clear and clear, interested friends can learn, I believe it will be helpful after reading.

This paper describes the basic operation of MongoDB database with an example. Share with you for your reference, the details are as follows:

1. Test2 cannot be found until database > use test > db.test.insert ({"name": 1}) is inserted. View the database > show dbs3. Delete database > use test > db.dropDatabase () 4. Create a collection 4.1 A collection of concepts is a set of documents, equivalent to multiple records. > db.title.insert ({"name": "hyx"}) is inserted to create the collection 5. View the collection > show collections6. Delete collection > use test > db.title.drop () 7. Insert document 7.1 document concept multiple keys and their associated values are placed together in an orderly manner. The document is similar to json data > db.file.insert ({name: "huangyuxin", age:11}) 8. View the document > db.files.find () 9. Insert document > document= ({by: "hyx"}) {"by": "hyx"} > db.file.insert (document) WriteResult ({"nInserted": 1}) > db.file.find () {"_ id": ObjectId ("5c6e8a060fc535200b893f29"), "name": "huangyuxin", "age": 11} {"_ id": ObjectId ("5c6e8b1c0fc535200b893f2a"), "by": "hyx"} > 10. Insert multiple > var res = db.file.insertMany ([{"b": 3}, {'centering: 4}]) > res {"acknowledged": true, "insertedIds": [ObjectId ("5c6e8bba0fc535200b893f2b"), ObjectId ("5c6e8bba0fc535200b893f2c")]} > db.file.find () {"_ id": ObjectId ("5c6e8a060fc535200b893f29"), "name": "huangyuxin" "age": 11} {"_ id": ObjectId ("5c6e8b1c0fc535200b893f2a"), "by": "hyx"} {"_ id": ObjectId ("5c6e8bba0fc535200b893f2b"), "b": 3} {"_ id": ObjectId ("5c6e8bba0fc535200b893f2c"), "c": 4} > 11. Update document > db.file.update ({"name": "huangyuxin"}, {$set: {"name": "hyx"}) WriteResult ({"nMatched": 1, "nUpserted": 0, "nModified": 1}) > db.file.find () {"_ id": ObjectId ("5c6e8a060fc535200b893f29"), "name": "hyx", "age": 11} {"_ id": ObjectId ("5c6e8b1c0fc535200b893f2a") "by": "hyx"} {"_ id": ObjectId ("5c6e8bba0fc535200b893f2b"), "b": 3} {"_ id": ObjectId ("5c6e8bba0fc535200b893f2c"), "c": 4} {"_ id": ObjectId ("5c6e8cdf0fc535200b893f2d"), "name": "hyx"} > db.file.save ({"_ id": ObjectId ("5c6e8b1c0fc535200b893f2a"), "name": "hyx"}) WriteResult ({"nMatched": 1) "nUpserted": 0, "nModified": 1}) > db.file.find () {"_ id": ObjectId ("5c6e8a060fc535200b893f29"), "name": "hyx", "age": 11} {"_ id": ObjectId ("5c6e8b1c0fc535200b893f2a"), "name": "hyx"} {"_ id": ObjectId ("5c6e8bba0fc535200b893f2b"), "b": 3} {"_ id": ObjectId ("5c6e8bba0fc535200b893f2c") "c": 4} {"_ id": ObjectId ("5c6e8cdf0fc535200b893f2d"), "name": "hyx"} > 12. Delete document 12.1 Delete specified document > db.title.find () {"_ id": ObjectId ("5c6e89060fc535200b893f27"), "name": "yx"} > db.file.find () {"_ id": ObjectId ("5c6e8a060fc535200b893f29"), "name": "hyx", "age": 11} {"_ id": ObjectId ("5c6e8b1c0fc535200b893f2a"), "name": "hyx"} {"_ id": ObjectId ("5c6e8bba0fc535200b893f2b") "b": 3} {"_ id": ObjectId ("5c6e8bba0fc535200b893f2c"), "c": 4} {"_ id": ObjectId ("5c6e8cdf0fc535200b893f2d"), "name": "hyx"} > db.file.remove ({"b": 3}) WriteResult ({"nRemoved": 1}) > db.file.find () {"_ id": ObjectId ("5c6e8a060fc535200b893f29"), "name": "hyx" "age": 11} {"_ id": ObjectId ("5c6e8b1c0fc535200b893f2a"), "name": "hyx"} {"_ id": ObjectId ("5c6e8bba0fc535200b893f2c"), "c": 4} {"_ id": ObjectId ("5c6e8cdf0fc535200b893f2d") "name": "hyx"} > 12.2 Delete all documents > db.file.deleteMany ({}) 12.3 Delete multiple documents > db.file.deleteMany ({status: 1}) Delete all documents with status equal to 1 in the current library 13. Conditional expression 13.1$ gt greater than query data with age greater than 0 > db.title.find ({age: {$gt: 0}}) {"_ id": ObjectId ("5c6f7d633ea8783bbfb7fd5e"), "age": 10} > 13..2$ lt less than 13.3$ gte greater than or equal to $lte less than or equal to query data with age greater than or equal to 0 > db.title.find ({age: {$gte: 1}}) 13.4 greater than less than > db.title.find ({age: {$lt:13) $gt:10}}) {"_ id": ObjectId ("5c6f7ded3ea8783bbfb7fd5f"), "age": 12} {"_ id": ObjectId ("5c6f7e833ea8783bbfb7fd60"), "age": 12} > 13.5$ ne is not equal to $eq equals 14. The $type operator $type operator retrieves matching data types in the collection based on BSON types. And return the result.

> db.title.find ({"name": {$type: 2}}) {"_ id": ObjectId ("5c6e89060fc535200b893f27"), "name": "yx"} > 15. Limit () query specified number of entries > db.title.find (). Limit (2) {"_ id": ObjectId ("5c6e89060fc535200b893f27"), "name": "yx"} {"_ id": ObjectId ("5c6f7d633ea8783bbfb7fd5e") "age": 10} > first {} put where condition Empty means to return all documents in the collection. The second {} specifies which columns are displayed and not displayed (0 means no display 1 means display). > db.title.find ({}, {"name": 1 16.skip 0}) .limit (1) {"name": "yx"} > 16.skip () skip a few pieces of data and do not easily use Skip to query, otherwise a large amount of data will lead to a sharp decline in performance, because the skip is numbered one by one, and more naturally slows down. 17.sort () 1 is in ascending order, while-1 is used in descending order. > db.title.find ({}, {'age':1,_id:0}). Sort ({age:1}) {} {"age": 10} {"age": 12} {"age": 12} > db.title.find ({}, {' age':1,_id:0}). Sort ({age:-1}) {"age": 12} {"age": 10} {} > 18. Index 18.1 create a single index 1 to create an index in ascending order for the specified The descending index is specified as-1 > db.title.createIndex ({"age": 1}) 18.2 create multiple indexes > db.title.createIndex ({"name": 1) "age":-1}) 18.3 View Index > db.col.getIndexes () 18.4 View Index size > db.col.totalIndexSize () 18.5 Delete all Collection Indexes > db.col.dropIndexes () 18.6 Delete specified Index > > db.title.dropIndex ({'age':1}) {"nIndexesWas": 2, "ok": 1} > read the above Do you have a further understanding of the basic operation of summarizing MongoDB database? if you want to learn more, you are welcome to follow the industry information channel.

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