MongoDB Second day -CRUD

The first chapter the INSERT

• If a document fails to be inserted during the insert process, all documents before it succeed, including all subsequent documents fail.
• Mongodb only performs basic checks. A maximum of 16MB is required. It is easy to insert illegal data. So it’s only open to trusted applications.
• Mainstream language driver, data insertion time to do verification. Such as whether the document is too large, whether the document contains strings other than UTF8, and whether it uses unrecognized types.

Db.collection.insert () inserts one or more documents into the collection

Insert ({name:'frist doc',age:'1',tag:'frist insert doc'}) WriteResult({"nInserted" : 1}) multiple operations: Db.ins. insert([{name:' SEC doc',age:'2',tag:' SEC insert doc'}, {name:' THR doc',age:'3',tag:' THR insert doc'}])  BulkWriteResult({ "writeErrors" : [ ], "writeConcernErrors" : [ ], "nInserted" : 2, "nUpserted" : 0, "nMatched" : 0, "nModified" : 0, "nRemoved" : 0, "upserted" : [ ] })Copy the code

2. The db. Collection. InsertOne () to insert a new document in the collection.

Db.ins. insertOne({name:'four doc',age:'4',tag:'four insert doc'}) {" indispensable ": true, "insertedId" : ObjectId("5c85f85806bbda89cc0dc44a") }Copy the code

3. The db. Collection. InsertMany () more than insert a new document in the collection.

Db.ins. insertMany([{name:'five doc',age:'5',tag:'five insert doc'}, {name:'six doc',age:'7',tag:'six insert doc'}, {name:'seven doc',age:'8',tag:'seven insert doc'}]) {" indispensable ": true, "insertedIds" : [ ObjectId("5c85f93806bbda89cc0dc44b"), ObjectId("5c85f93806bbda89cc0dc44c"), ObjectId("5c85f93806bbda89cc0dc44d") ] }Copy the code

4. Perform other operations that can be inserted

Db.collection.update () with upsert true db.collection.updateOne() with upsert true db.collection.updatemany () with upsert true db.collection.updatemany () When the upsert is true / / db. The third parameter collection. The findAndModify () when the upsert is true * * db in the collection. The findAndModify () when the upsert is true * * Db. Collection. FindOneAndReplace () when the upsert is true

The second chapter the UPDATE

• $set new keys and update keys
• $unset the delete key
• The value of the $INCr key can be increased or decreased. The value of the key can only be a number. The key type can only be an integer, a long integer, or a double precision floating point.
• $push adds elements to the end of the array

1. Db.collection. update Updates records

Insert test data

Db.inventory.insertmany ([{item: "canvas", qty: 100, size: {h: 28, w: 35.5, uom: "cm"}, status: "A"}, {item: "Journal ", Qty: 25, size: {h: 14, W: 21, UOM: "cm"}, status: "A"}, {item: "mat", Qty: 85, size: {h: 27.9, w: 35.5, UOM: "CM"}, status: "A"}, {item: "mousepad", Qty: 25, size: {h: 19, w: 22.85, UOM: "cm"}, status: "P"}, {item: "notebook", qty: 50, size: {h: 8.5, w: 11, uom: "in"}, status: "P"}, {item: "paper", qty: 100, size: {h: 8.5, w: 11, uom: "in"}, status: a "D"}, {item: "planner", qty: 75, size: {h: 22.85, w: 30, uom: "cm"}, the status: "D"}, {item: "Postcard ", Qty: 45, size: {H: 10, W: 15.25, UOM:" CM "}, status: "A"}, {item: "Sketchbook ", qty: 80, size: {h: 14, W: 21, UOM: "CM"}, status: "A"}, {item: "Sketch pad", QTY: 95, size: {h: 22.85, W: 30.5, UOM: "cm" }, status: "A" } ]); { "acknowledged" : true, "insertedIds" : [ ObjectId("5cbd706b35bc4d3801a312d1"), ObjectId("5cbd706b35bc4d3801a312d2"), ObjectId("5cbd706b35bc4d3801a312d3"), ObjectId("5cbd706b35bc4d3801a312d4"), ObjectId("5cbd706b35bc4d3801a312d5"), ObjectId("5cbd706b35bc4d3801a312d6"), ObjectId("5cbd706b35bc4d3801a312d7"), ObjectId("5cbd706b35bc4d3801a312d8"), ObjectId("5cbd706b35bc4d3801a312d9"), ObjectId("5cbd706b35bc4d3801a312da") ] }Copy the code

2. Db. Collections. UpdateOne () to update the first qualified documents

Db.inventore. find({item:"paper"}) {"_id" : ObjectId(" 5c85fCD906bbDA89CC0dc450 "), "item" :"paper", "qty" : 100, "size" : {" h ": 8.5," w ": 11," uom ":" in "}, "status" : "D"} {" _id ": ObjectId(" 5C861B4B274C7C6EFF9c0106 "), "item" : "paper", "qTY" : 100, "size" : {" H ": 8.5, "w" : 11, "uom" : Db.inventory. updateOne({item: "paper"}, {$set: {"size. Uom ": {$set: {"size. {"matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : Find ({item:"paper"}) {"_id" : ObjectId(" 5c85fCD906bbDA89CC0dc450 "), "item" : "Paper", "qty" : 100, the "size" : {" h ": 8.5," w ": 11," uom ":" cm "}, "status" : "P", "lastModified" : ISODate(" 2019-03-11t08:38:32.820z ")} {"_id" : ObjectId(" 5C861b4b274C7c6eff9c0106 "), "item" : "paper", "qty" : 100, "size" : {" h ": 8.5," w ": 11," uom ":" in "}, "status" : "D"}Copy the code

3. The db. Collection. UpdateMany () more than update document, if the upsert to true. If no document is saved, the document is inserted.

Db.inventory. find({qty:{$lt:50}}) {"_id" : ObjectId(" 5c85fCD906bbDA89CC0dc44e "), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "status" : "A" } { "_id" : ObjectId(" 5C85FCD906BBDA89CC0DC452 "), "item" : "Postcard "," QTY ": 45, "size" : {" H" : 10, "w" : 15.25, "Uom" : "cm" }, "status" : "A" } { "_id" : ObjectId("5c861b4b274c7c6eff9c0102"), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "status" : "A" } { "_id" : ObjectId("5c861b4b274c7c6eff9c0104"), "item" : "Mousepad," "qty" : 25, "size" : {" h ": 19" w ": 22.85," uom ":" cm "}, "status" : "P"} {" _id ": ObjectId(" 5C861B4B274C7C6EFF9C0108 "), "item" : "Postcard "," QTY ": 45, "size" : {" H" : 10, "w" : 15.25, "Uom" : Db.inventory. updateMany({"qty": {$lt: 50}}, {$set: {" sie.uom ": "in", status: {$set: {" sie.uom ": "in", status: {"matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : "matchedCount" : Find ({qty:{$lt:50}}) {"_id" : ObjectId(" 5c85fCD906bbDA89CC0dc44e "), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "in" }, "status" : "P", "lastModified" : ISODate(" 2019-03-11T08:41:16.569z ")} {"_id" : ObjectId(" 5C85fCD906bbDA89CC0DC452 "), "item" : "Postcard "," Qty ": 45, "size" : {" h ": 10," w ": 15.25," uom ":" in "}, "status" : "P", "lastModified" : ISODate(" 2019-03-11t08:41:16.570z ")} {"_id" : ObjectId(" 5C861b4b274C7c6eff9c0102 ", "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "in" }, "status" : "P", "lastModified" : ISODate(" 2019-03-11t08:41:16.570z ")} {"_id" : ObjectId(" 5C861b4b274C7c6eff9c0104 "), "item" : 25, "size" : {" h ": 19" w ": 22.85," uom ":" in "}, "status" : "P", "lastModified" : ISODate(" 2019-03-11T08:41:16.570z ")} {"_id" : ObjectId(" 5C861B4B274C7C6EFF9c0108 "), "item" : "Postcard ", "qty" : 45, "size" : {" h ": 10," w ": 15.25," uom ":" in "}, "status" : "P", "lastModified" : ISODate (" the 2019-03-11 T08: shalt. 570 z ")}Copy the code

4. Db.collection.replaceone () replaces the first qualifying document and passes the new parameter to replaceOne. The ID field cannot be replaced.

Db.inventore. find({item:"paper"}) {"_id" : ObjectId(" 5c85fCD906bbDA89CC0dc450 "), "item" :"paper", "qty" : 100, "size" : {" h ": 8.5," w ": 11," uom ":" cm "}, "status" : "P", "lastModified" : ISODate(" 2019-03-11t08:38:32.820z ")} {"_id" : ObjectId(" 5C861b4b274C7c6eff9c0106 "), "item" : "paper", "qty" : 100, "size" : {"h" : 8.5, "w" : 11, "UOM" : "in"}, "status" : "D"} Execute update command db.inventory.replaceOne({item: "paper" }, { item: "paper", instock: [ { warehouse: "A", qty: 60 }, { warehouse: "B", qty: {" indispensable ": true, "matchedCount" : 1, "modifiedCount" : 1}}) {" indispensable" : true, "matchedCount" : 1, "modifiedCount" : Db.invento.find ({item:"paper"}) {"_id" : ObjectId(" 5c85fCD906bbDA89CC0dc450 "), "item" :"paper", "instock" : [ { "warehouse" : "A", "qty" : 60 }, { "warehouse" : "B", "qty" : 40 } ] } { "_id" : ObjectId(" 5C861B4B274C7C6EFF9c0106 "), "item" : "paper", "qTY" : 100, "size" : {" H ": 8.5, "w" : 11, "uom" : Db.test.find () {"_id" : ObjectId(" 5FD07c9198ada1CE0d1e52a5 "), "name" : ObjectId(" 5FD07c9198ada1ce0d1e52a5 ") "joe", "friends" : 32, "enemies" : 2 } db.test.replaceOne( {'name':'joe'}, {'name':'joe','relationships':{"friends" : 32,"enemies" : 2}} ) { "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 } db.test.find() { "_id" : ObjectId("5fd07c9198ada1ce0d1e52a5"), "name" : "joe", "relationships" : { "friends" : 32, "enemies" : 2}} bill - repli: PRIMARY > db. Collections. UpdateONE, updateMany, updateReplace when upsert is true, if the record does not exist the insert new record try { db.inventory.updateOne( { "name" : "Pizza Rat's Pizzaria" }, { $set: {"_id" : 4, "violations" : 7, "borough" : "Manhattan" } }, { upsert: true } ); } catch (e) { print(e); } result: Because there is no condition to match this record. So a new record is inserted. { "acknowledged" : true, "matchedCount" : 0, "modifiedCount" : 0, "upsertedId" : 4 } { "_id" : 4, "name" : "Pizza Rat's Pizzaria", "borough" : "Manhattan", "violations" : 7 } db.blog.find() { "_id" : ObjectId("5fc5a6a3e78f91ca2839cb16"), "name" : "a" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb17"), "name" : "b" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb18"), "name" : "c" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb19"), "name" : "d" }Copy the code

5. Add/update field SET and delete field unset

Db.blog. update({},{$set:{'num':''}}) WriteResult({"nMatched" : 1, "nUpserted" : 0, "nModified" : 0) 1 }) db.blog.find() { "_id" : ObjectId("5fc5a6a3e78f91ca2839cb16"), "name" : "a", "num" : "" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb17"), "name" : "b" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb18"), "name" : "c" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb19"), "name" : Db.blog. update({'name':'c'},{$set:{'num':'2'}}) WriteResult({"nMatched" : 1, "nUpserted") : 0, "nModified" : 1 }) db.blog.find() { "_id" : ObjectId("5fc5a6a3e78f91ca2839cb16"), "name" : "a", "num" : "" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb17"), "name" : "b" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb18"), "name" : "c", "num" : "2" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb19"), "name" : Db.blog. update({},{$set:{'num':''}},{multi:1}) WriteResult({"nMatched" : 4, "nUpserted" : 0, "nModified" : 3 }) db.blog.find() { "_id" : ObjectId("5fc5a6a3e78f91ca2839cb16"), "name" : "a", "num" : "" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb17"), "name" : "b", "num" : "" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb18"), "name" : "c", "num" : "" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb19"), "name" : "d", "num" : ""} add conditions for name: c, delete a field when the blog. Update ({' name ':' c '}, {$unset: {' num ':'}}) WriteResult ({" nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) db.blog.find() { "_id" : ObjectId("5fc5a6a3e78f91ca2839cb16"), "name" : "a", "num" : "" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb17"), "name" : "b", "num" : "" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb18"), "name" : "c" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb19"), "name" : "D ", "num" : ""} Delete the first record without conditions. db.blog.update({},{$unset:{'num':''}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) db.blog.find() { "_id" : ObjectId("5fc5a6a3e78f91ca2839cb16"), "name" : "a" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb17"), "name" : "b", "num" : "" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb18"), "name" : "c" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb19"), "name" : "D ", "num" : ""} delete all existing files without condition. db.blog.update({},{$unset:{'num':''}},{multi:1}) WriteResult({ "nMatched" : 4, "nUpserted" : 0, "nModified" : 2 }) db.blog.find() { "_id" : ObjectId("5fc5a6a3e78f91ca2839cb16"), "name" : "a" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb17"), "name" : "b" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb18"), "name" : "c" } { "_id" : ObjectId("5fc5a6c3e78f91ca2839cb19"), "name" : Insert (post) WriteResult({"nInserted" : 1}) db.blog.find() {"_id" : ObjectId("5fc4ba63bad2853e0468a3c8"), "title" : "My Blog Post", "connect" : "Here is my blog post.", "date" : Pretty () {"_id" : ISODate(" 2020-11-30T9:24:41.117z ")} add a comment to db.blog.find(). Pretty () {"_id" : ObjectId("5fc5a524e78f91ca2839cb15"), "title" : "My Blog Post", "connect" : "Here is my blog post.", "date" : [] db.blog.update({'title':'My blog Post'}, Post) WriteResult({'title':'My blog Post'})  "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) db.blog.find().pretty() { "_id" : ObjectId("5fc5a524e78f91ca2839cb15"), "title" : "My Blog Post", "connect" : "Here is my blog post.", "date" : ISODate(" 2020-12-01T02:06:19.189z "), "Comments" : []}Copy the code

6.$INCR increases and decreases

Update ({"game" : "pinball", "user" : "Joe "},{$inc:{'score':50}}) WriteResult({"nMatched" : 1, "nUpserted" : 0, "nModified" : 1}) because there is no score Db.games.find () {"_id" : ObjectId(" 5FD08A299EF0890CE971e161 "), "game" : "pinball", "user" : "Joe ", "score" : 50} Now score increases by 10000 db.games.update({"game" : "pinball", "user" : "joe"},{$inc:{'score':10000}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : Find () {"_id" : ObjectId(" 5fd08a299EF0890CE971e161 "), "game" : "pinball", "user" : "Joe ", "score" : 10050} Now score minus 5000 db.games.update({"game" : "pinball", "user" : "joe"},{$inc:{'score':-5000}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : Find () {"_id" : ObjectId(" 5fd08a299EF0890CE971e161 "), "game" : "pinball", "user" : "joe", "score" : 5050 }Copy the code

7. Array push,pull,pop,$(subscript)

A list that can be referenced by index and can also be used as a data set

$push adds an element to the end of the array. If the array does not exist, create a new array db.games.find() {"_id" : ObjectId(" 5FD08A299EF0890CE971e161 "), "game" : "pinball", "user" : "joe", "score" : 5050, "comments" : [ { "content" : "very good", "email" : "[email protected]" }, { "content" : "very nice", "email" : "[email protected]" }, 123, 456, 789, { "content" : "very bad", "eamil" : "[email protected]" }, { "content" : "very not nice", "email" : "[email protected]" } ] } db.games.find().pretty() { "_id" : ObjectId("5fd08a299ef0890ce971e161"), "game" : "pinball", "user" : "joe", "score" : 5050, "comments" : [ { "content" : "very good", "email" : "[email protected]" }, { "content" : "very nice", "email" : "[email protected]" }, 123, 456, 789, { "content" : "very bad", "eamil" : "[email protected]" }, { "content" : "very not nice", "email" : Db.game.deleteone ({' Comments ':123}) {" indispensable ": true, "deletedCount" : 0} Use $pull to remove the specified array element. Db.games. update({},{$pull:{'comments':123}}) WriteResult({"nMatched" :1, "nUpserted" :1) 0, "nModified" : 1 }) db.games.update( {}, {$pull:{'comments':456}} ) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) db.games.update( {}, {$pull:{'comments':789}} ) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) db.games.find().pretty() { "_id" : ObjectId("5fd08a299ef0890ce971e161"), "game" : "pinball", "user" : "joe", "score" : 5050, "comments" : [ { "content" : "very good", "email" : "[email protected]" }, { "content" : "very nice", "email" : "[email protected]" }, { "content" : "very bad", "eamil" : "[email protected]" }, { "content" : "very not nice", "email" : Update ({},{$pop:{'comments':-1}}) WriteResult({"nMatched" : 1, "nUpserted" : 0, "nModified" : Update ({},{$pop:{'comments':1}}) WriteResult({"nMatched" :1, "nUpserted" :1) 0, "nModified" : 1 }) db.games.find().pretty() { "_id" : ObjectId("5fd08a299ef0890ce971e161"), "game" : "pinball", "user" : "joe", "score" : 5050, "comments" : [ { "content" : "very nice", "email" : "[email protected]" }, { "content" : "very bad", "eamil" : "[email protected]" } ] } db.games.update( {"score" : 5050}, {$push: {' top 10 ': {$each:,7,8,9,10,11,12,13,14,15,16,17,18 [6]}}}) WriteResult ({" nMatched ": 1," nUpserted ": 0, "nModified" : 1 }) db.games.find().pretty() { "_id" : ObjectId("5fd08a299ef0890ce971e161"), "game" : "pinball", "user" : "joe", "score" : 5050, "comments" : [ { "content" : "very nice", "email" : "[email protected]" }, { "content" : "very bad", "eamil" : "[email protected]" } ], "top10" : [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25]} To limit the number of elements, use $push and $slice together. Slice must be a negative integer to ensure that the specified length is not exceeded. Although I pushed 26 to 33 8 elements. But only the last five elements remain. Use $sort when you can clean up again. Adding data requires cleaning up. db.games.update( {"score" : 5050}, {$push: {' top 10 ': {$each:,27,28,29,30,31,32,33 [26], $slice: - 5}}}) WriteResult ({" nMatched ": 1," nUpserted ": 0, "nModified" : 1 }) db.games.find().pretty() { "_id" : ObjectId("5fd08a299ef0890ce971e161"), "game" : "pinball", "user" : "joe", "score" : 5050, "comments" : [ { "content" : "very nice", "email" : "[email protected]" }, { "content" : "very bad", "eamil" : "[email protected]" } ], "top10" : [29, 30, 31, 32, 33]} Only part of the array can be modified by subscripting the email. Def db.games.update({'game':'pinball'},{$set:{'comments.0. Email ':'[email protected]'}}) WriteResult({"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) db.games.find().pretty() { "_id" : ObjectId("5fd08a299ef0890ce971e161"), "game" : "pinball", "user" : "joe", "score" : 5050, "comments" : [ { "content" : "very nice", "email" : "[email protected]" }, { "content" : "very bad", "eamil" : "[email protected]" } ], "top10" : [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]} Modify values by subscript. You can use the $sign instead of the subscript. Because sometimes only a query can determine the subscript. Use $to omit the subscript address. Update ({'comments.content':'very nice'},{$set:{'comments.$. Content ':'double very nice'}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) db.games.find().pretty() { "_id" : ObjectId("5fd08a299ef0890ce971e161"), "game" : "pinball", "user" : "joe", "score" : 5050, "comments" : [ { "content" : "double very nice", "email" : "[email protected]" }, { "content" : "very bad", "eamil" : "[email protected]" } ], "top10" : [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]}Copy the code

8. Upsert Updates when the upsert update record exists. Insert a new record when the upsert update record does not exist.

db.email.update({'name':'upsert'}, ... {$set:{'name':'upsert',email:'[email protected]'}} ... ) WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 }) db.email.find().pretty() { "_id" : ObjectId("5fd09fb79ef0890ce971e166"), "name" : "abc", "email" : "[email protected]" } { "_id" : ObjectId("5fd09fb79ef0890ce971e167"), "name" : "def", "email" : "[email protected]" } { "_id" : ObjectId("5fd09fb79ef0890ce971e168"), "name" : "ghi", "email" : "[email protected]" } db.email.update({'name':'upsert'}, {$set:{'name':'upsert',email:'[email protected]'}},true ) WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : ObjectId("5fd718a37de2d14d3a30c553") }) db.email.find().pretty() { "_id" : ObjectId("5fd09fb79ef0890ce971e166"), "name" : "abc", "email" : "[email protected]" } { "_id" : ObjectId("5fd09fb79ef0890ce971e167"), "name" : "def", "email" : "[email protected]" } { "_id" : ObjectId("5fd09fb79ef0890ce971e168"), "name" : "ghi", "email" : "[email protected]" } { "_id" : ObjectId("5fd718a37de2d14d3a30c553"), "name" : "upsert", "email" : "[email protected]"} $setOneInsert Creates and assigns a field to a document, but the field value does not change in subsequent updates.Copy the code

The third chapter the DELETE

1. The db. Collections. DeleteOne delete qualified first document ()

Db.inventory. deleteOne({status: "D"}) {" indispensable ": true, "deletedCount" : 1} A record was deletedCopy the code

2. Db. Collection. DeleteOne () to delete all conform to the conditions of the document

Db.inventory. deleteMany({status: "A"}) {" indispensable ": true, "deletedCount" : 7} Prompt to delete 7 recordsCopy the code

3. You can also run the delete command

Db. Collection. FindOneAndDelete () sorting options. This option allows you to delete the first document sorted in the specified order. Db. Collection. FindAndModify () sorting options. This option allows you to delete the first document sorted in the specified order. Example: db. Ins. FindAndModify ({query: {' age ', '9'}, remove: true})Copy the code

Db.col.drop () drops a collection

Quickly delete all records.Copy the code

The fourth chapter the FIND

• The value must be constant for the document to be queried

1. Db.collection.find ()/db.collection.find({}) Queries all records

Select * from table db.invento.find () {"_id" : ObjectId(" 5C85fCD906bbDA89CC0dc44e "), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "status" : "A" } { "_id" : ObjectId(" 5C85fCD906bbDA89CC0DC44F "), "item" : "notebook", "qTY" : 50, "size" : {" H ": 8.5, "w" : 11, "uom" : "in" }, "status" : "A" } { "_id" : ObjectId("5c85fcd906bbda89cc0dc450"), "item" : "paper", "qty" : 100, "size" : {" h ": 8.5," w ": 11," uom ":" in "}, "status" : "D"} db. The inventory. The find ({}) {" _id ": ObjectId("5c85fcd906bbda89cc0dc44e"), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "status" : "A" } { "_id" : ObjectId("5c85fcd906bbda89cc0dc44f"), "item" : "notebook", "qty" : 50, "size" : {" h ": 8.5," w ": 11," uom ":" in "}, "status" : "A"} {" _id ": ObjectId (" 5 c85fcd906bbda89cc0dc450"), "item" : "Paper", "qty" : 100, the "size" : {" h ": 8.5," w ": 11," uom ":" in "}, "status" : "D"}Copy the code

Db.inventory. find({status: “D”}

SELECT * FROM inventory WHERE status = "D" db.inventory.find({status: "D"}) {" _id ": ObjectId (" 5 c85fcd906bbda89cc0dc450"), "item" : "paper", "qty" : 100, the "size" : {" h ": 8.5," w ": 11," uom ": "in" }, "status" : "D" } { "_id" : ObjectId("5c85fcd906bbda89cc0dc451"), "item" : "planner", "qty" : 75, "size" : {" h ": 22.85," w ": 30," uom ":" cm "}, "status" : "D"}Copy the code

3. IN the query

Db.inventory. find({status: {$in: ["A", "D"]}}) MYSQL > inventory SELECT * FROM inventory WHERE status in ("A", "D") However, the official recommendation is to use in to query. db.inventory.find( { status: { $in: [ "A", "D" ] } } ) { "_id" : ObjectId("5c85fcd906bbda89cc0dc44e"), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "status" : "A" } { "_id" : ObjectId(" 5C85fCD906bbDA89CC0DC44F "), "item" : "notebook", "qTY" : 50, "size" : {" H ": 8.5, "w" : 11, "uom" : "in" }, "status" : "A" } { "_id" : ObjectId("5c85fcd906bbda89cc0dc450"), "item" : "paper", "qty" : 100, "size" : {" h ": 8.5," w ": 11," uom ":" in "}, "status" : "D"}Copy the code

4. The AND query

The db. The inventory. The find ({status: "A", qty: {$lt: 30}}) and operation. Find documents where status is equal to A and QTY is less than 30. Select * from inventory WHERE status="A" and qty<30 db.inventory.find({status:"A",qty:{$lt:30}}) {"_id" : ObjectId("5c85fcd906bbda89cc0dc44e"), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "status" : "A" }Copy the code

5. The OR query

Db.inventory. find({$or:[{status:"A"},{qty:{$lt:30}}]}) SELECT * FROM inventory WHERE ($or:[{status:"A"},{$lt:30}}]} status = "A" OR qty < 30 db.inventory.find({$or:[{status:"A"},{qty:{$lt:30}}]}) { "_id" : ObjectId("5c85fcd906bbda89cc0dc44e"), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "status" : "A" } { "_id" : ObjectId("5c85fcd906bbda89cc0dc44f"), "item" : "notebook", "qty" : 50, "size" : {" h ": 8.5," w ": 11," uom ":" in "}, "status" : "A"}Copy the code

6.SORT /Pretty /Limit /Skip to return the rest of the document

Db.inventory.find ().sort({name:1}).pretty() sort the name field and beautify the output. db.ins.find().sort({name:1}).pretty() { "_id" : ObjectId("5c85f93806bbda89cc0dc44b"), "name" : "five doc", "age" : "5", "tag" : "five insert doc" } { "_id" : ObjectId("5c85f85806bbda89cc0dc44a"), "name" : "four doc", "age" : "4", "tag" : "four insert doc" } { "_id" : ObjectId("5c85f7ad06bbda89cc0dc447"), "name" : "frist doc", "age" : Db.email.count () 5 Limit () db.email.find().limit(2) {"_id" : ObjectId("5fd09fb79ef0890ce971e166"), "name" : "abc", "email" : "[email protected]" } { "_id" : ObjectId(" 5fd09fb79EF0890ce971e167 "), "name" : "def", "email" : "[email protected]"} Skip the first two results and return the remaining results. db.email.find().skip(2) { "_id" : ObjectId("5fd09fb79ef0890ce971e168"), "name" : "ghi", "email" : "[email protected]" } { "_id" : ObjectId("5fd718a37de2d14d3a30c553"), "name" : "up", "email": "[email protected]" } { "_id" : ObjectId("5fd71a2a2f1e32c5f863d32b"), "name" : "abc", "email" : "[email protected]" }Copy the code

7. Query array documents

Db.ins. insert({"name" : "11.sz", "age" : "11", "tags":["java","kpop","china"]}) db.ins.insert({name:'12',age:12,tags:[{'code':'java','music':'kpop'}]}) db.ins.find({"tags.code":'java'}).pretty() { "_id" : ObjectId("5ee739cb2d413b0b41df886e"), "name" : "12", "age" : 12, "tags" : [ { "code" : "java", "music" : "kpop" } ] } db.ins.find({"tags":'java'}).pretty() { "_id" : ObjectId("5ee736c62d413b0b41df886d"), "name" : "11.sz", "age" : "11", "tags" : [" Java ", "kpop", "China"]} the users. The find ({tags: [" Java "]}) exact match array document, Db.users.find ({tags:[" Java ","mongodb"]}) matches the array document exactly, Db.users. find({tags:[" Java ","bike"]}) matches db.users.find({tags:[" Java ","bike"]}) matches db.users.find({tags:[" Java ","bike"]}) Db.users. Find ({tags:" Java "}) fuzzy matching, as long as tags with Java to show. Db.usersCopy the code

8. Fuzzy query

Select * from users where name like '%a%' db.users.find({name:/.*a.*/}) Db.users. find({name:/.*a$/}) db.users.find({name:/.*a$/}) db.users.find({name:/.*a$/})Copy the code

9. Document nested query

(example) {"_id" : ObjectId(" 5b58b9544983f690C7AB9687 "), "name" : "baby3", "age" : "baby3", "age" : 18, "address" : { "country" : "china", "city" : "hangzhou", "district" : "xihu", "dd" : "zhongguancunroad 10" } } { "_id" : ObjectId("5b58b9784983f690c7ab9688"), "name" : "xiaowang", "age" : 19, "address" : { "country" : "china", "city" : "shanghai", "district" : "pudong", "dd" : "Sjtu Park 10"}} The query should contain the outer field and the inner field, can not be in order to query. You can also query strictly in order. Db.users. find({"address.country":' China '}) country db.users.find({"address.country":' China '}) country Db.users. find({"address.city":'hangzhou'}) db.users.find({age:18,"address.city":'hangzhou'}) db.users.find({age:18,"address.city":'hangzhou'}) Db.users. find({age:{$lt:18},"address.city":' Hangzhou '}) can be restricted by conditions such as the 0 element that is less than 18 years old. Db.orders. find({'item.0. Count ':{$lt:2}}) multiple conditions and query db.orders.find({"item.count":{$gt:0,$lte:100}}) projection (map) returns specific fields Db.users. find({age:18},{name:1,age:1}) where age is 18. Db.users. find({age:{$gt:29}},{name:1,age:1}); db.users.find({age:{$gt:29},{name:1,age:1}); Db.users. find({age:{$gt:29}},{name:0}); db.users.find({age:{$gt:29}},{name:0}); Do not return the name field, everything else is returnedCopy the code

9. Projection (returns only specific fields)/ de-redo/aggregate

Projection (mapping) returns a specific field, _id if not specified. Flag as 1 for fields you want to return, such as name:1. Identify 0 for unwanted fields such as age:0. Db.users. find({age:18},{name:1,age:1}) where age is 18. Db.users. find({age:{$gt:29}},{name:1,age:1}); db.users.find({age:{$gt:29},{name:1,age:1}); Db.users. find({age:{$gt:29}},{name:0}); db.users.find({age:{$gt:29}},{name:0}); Db.users. Distinct ("name") db.Orders. Distinct ("items. Count ") db.Orders. Db.orders. distinct("item.count ",{age:18}) db.orders.distinct("item.count ",{age:18}) db.orders.distinct("item.count ",{age:18}) db.orders.distinct("item.count ",{age:18}) Db.users. Distinct ("city") DB.users. Distinct ("address.city") is equivalent to the items.count field Db. runCommand({distinct:"users",key:"name"}) For performance, use indexes as much as possible. Nodes can be queried preferentially. There are three types of statistical analysis: aggregation functions (early features), aggregation pipelines, and MapReduce (for big data analysis). Simply use the group method. 3.4 Expired, it is recommended to use a new aggregation. Db.collections. aggregate()+$group or db.collections.mapreduce Group db.users. Group ({key:{age:1}, cond:{age:{$gt:16}}, reduce:function(curr,result){ result.total +=1; Db.orders. Grop ({key:{name:1}, cond:{}, initial:{total:0}) reduce:function(curr.result){ result.total += curr.price; Db.orders. Group ({key:{name:1}, cond:{}, initial:{total:0}) reduce:function(curr,result){ result.total +=1; }, initial:{total:0}} db.orders. Group ({key:{name:1}, cond:{}, reduce:function(curr,result){ result.total =curr.price }, initial:{total:0} } )Copy the code

10 Null value query

Db.a.type () {"_id" : ObjectId(" 5fd9b25c1d2a682a33b3AB90 "), "y" : null} {"_id" : ObjectId("5fd9b25c1d2a682a33b3ab91"), "y" : 1 } { "_id" : ObjectId("5fd9b25c1d2a682a33b3ab92"), "y" : Db.a.type ({'y':null}) {"_id" : ObjectId(" 5fd9b25c1d2a682a33b3AB90 "), "y" : ObjectId(" 5fd9b25c1d2a682a33b3AB90 "), "y" : Db.a.type ({'z':null}) {"_id" : ObjectId(" 5FD9b25c1d2a682a33b3AB90 "), "y" : ObjectId(" 5FD9b25c1d2a682a33b3AB90 ") null } { "_id" : ObjectId("5fd9b25c1d2a682a33b3ab91"), "y" : 1 } { "_id" : ObjectId("5fd9b25c1d2a682a33b3ab92"), "y" : 2} Check whether z is null and whether a key exists. You can avoid the above problems. db.a.find({'z':{$in:[null],$exists:true}})Copy the code

11. The DB. The COLLECTION. The FIND added

Greater than or less than using find to show only 20 rows, Db.users. find({age:{$gt:18}}) db.users.find({age:{$gt:18,$lt:28}}) db.users.find({age:{$gt:18,$lt:28}}) Do it based on scope. The left and right can be included with GTE and LTECopy the code

FIND the operator