數據庫操作

查看：show dbs;

創建：use dbname; //?db.createCollection('collection_name');? ? 隱式創建，需要創建的數據庫中有表才表示創建成功

刪除：use dbname;?db.dropDatabase();? ?//?選擇好對應的數據庫，然后刪除

如下實例：

查看數據庫：

> show dbs; admin 0.000GB local 0.000GB test_1 0.000GB >

?創建數據庫：隱式創建，直接use不存在的數據庫

> use student; switched to db student

?查看沒有：因為沒有在這個數據庫中創建表，只有創建表后才創建成功

> use student; switched to db student > show dbs; admin 0.000GB local 0.000GB test_1 0.000GB

?下面表示創建成功：

> use student; switched to db student > show dbs; admin 0.000GB local 0.000GB test_1 0.000GB > > show collections; > > show tables; > db.createCollection('minstudent'); { "ok" : 1 } > show tables; minstudent > show dbs; admin 0.000GB local 0.000GB student 0.000GB test_1 0.000GB

?刪除數據庫：

> db.dropDatabase(); { "dropped" : "student", "ok" : 1 } >

數據文檔操作

這里的文檔類似與MySQL中的表，因為Mongodb是文檔數據庫，所以可以說是對文檔的操作；

創建：db.createCollection('collection_name')；

刪除：db.collection_name.drop();

查看：show collections;

如下實例：

創建

> use school; switched to db school > > db.createCollection('student'); { "ok" : 1 }

?刪除

> db.student.drop(); true

?查看

> db.teacher.insert({'name':'teacher1'}); WriteResult({ "nInserted" : 1 }) > show collections; teacher

文檔內容操作

插入數據：db.collection_name.insert({key:value})? 單個插入

? ? ? ? ? ? ? ? ? db.collection_name.insert({_id:value, key:value})?有_id的插入

? ? ? ? ? ? ? ? ? db.collection_name.insert([{key:value},{key:value}])? ?多個插入

查看：db.collection_name.find();? ? //?這里只例舉簡單的查詢方法，會單獨寫一篇文檔詳細說明查詢的方法

刪除：db.collection_name.remove(查詢表達式，選項)

修改：db.collection_name.update(查詢表達式，新值，選項)

如下實例：

插入

> db.student.insert({'name': 'wallace'}); WriteResult({ "nInserted" : 1 }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" }

?修改_id

> db.student.insert({'name': 'bbbb', '_id':111}); WriteResult({ "nInserted" : 1 }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "bbbb" } { "_id" : 111, "name" : "bbbb" }

?插入多條

> db.student.insert([{'age': 'bbbb', 'age':111, 'home': 'beijin'},{'age':'laowang', 'age': 1, 'home':'江西'}]); BulkWriteResult({"writeErrors" : [ ],"writeConcernErrors" : [ ],"nInserted" : 2,"nUpserted" : 0,"nMatched" : 0,"nModified" : 0,"nRemoved" : 0,"upserted" : [ ] }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "bbbb" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810567cdad789abb91899c"), "age" : 111, "home" : "beijin" } { "_id" : ObjectId("5c810567cdad789abb91899d"), "age" : 1, "home" : "江西"}

刪除數據

> db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "bbbb" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810567cdad789abb91899c"), "age" : 111, "home" : "beijin" } { "_id" : ObjectId("5c810567cdad789abb91899d"), "age" : 1, "home" : "江西" } { "_id" : ObjectId("5c810575cdad789abb91899e"), "age" : 111, "home" : "beijin" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "age" : 1, "home" : "江西" } > db.student.remove({home:'beijin'}); WriteResult({ "nRemoved" : 2 }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "bbbb" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810567cdad789abb91899d"), "age" : 1, "home" : "江西" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "age" : 1, "home" : "江西" } > db.student.remove({home:'江西'}, true); WriteResult({ "nRemoved" : 1 }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "bbbb" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "age" : 1, "home" : "江西" } >

修改

> db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "bbbb" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "age" : 1, "home" : "江西" } > db.student.update({home:'江西'},{home:北京}); 2019-03-08T09:00:31.981-0500 E QUERY [thread1] ReferenceError: \u5317\u4EAC is not defined : @(shell):1:32 > db.student.update({home:'江西'},{home:'北京'}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "bbbb" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "home" : "北京" }

修改二：$set?具體到某一個鍵值對的值

> db.student.insert({'name':'bbb',age:18, classmate:4}); WriteResult({ "nInserted" : 1 }) > db.student.update({name:'bbb'}, {$set:{'age':19}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "1111" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "home" : "北京" } { "_id" : ObjectId("5c835969043334857a7dbe85"), "name" : "aaa", "age" : 18, "classmate" : 3 } { "_id" : ObjectId("5c835973043334857a7dbe86"), "name" : "bbb", "age" : 19, "classmate" : 4 }

修改三：$unset?刪除某一對象的鍵值對

> db.student.update({name:'bbb'}, {$unset:{'age':19}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "1111" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "home" : "北京" } { "_id" : ObjectId("5c835969043334857a7dbe85"), "name" : "aaa", "age" : 18, "classmate" : 3 } { "_id" : ObjectId("5c835973043334857a7dbe86"), "name" : "bbb", "classmate" : 4 } >

修改列名

> db.student.update({name:'bbb'}, {$rename:{'name':'sc'}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "1111" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "home" : "北京" } { "_id" : ObjectId("5c835969043334857a7dbe85"), "name" : "aaa", "age" : 18, "classmate" : 3 } { "_id" : ObjectId("5c835973043334857a7dbe86"), "classmate" : 4, "sc" : "bbb" } >

增加值

> db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "1111" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "home" : "北京" } { "_id" : ObjectId("5c835969043334857a7dbe85"), "name" : "aaa", "age" : 37, "classmate" : 3 } { "_id" : ObjectId("5c835973043334857a7dbe86"), "classmate" : 4, "sc" : "bbb" } > db.student.update({name:'aaa'},{$inc:{age:10}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.student.find(); { "_id" : ObjectId("5c810428cdad789abb91899a"), "name" : "wallace" } { "_id" : ObjectId("5c810441cdad789abb91899b"), "name" : "1111" } { "_id" : 111, "name" : "bbbb" } { "_id" : ObjectId("5c810575cdad789abb91899f"), "home" : "北京" } { "_id" : ObjectId("5c835969043334857a7dbe85"), "name" : "aaa", "age" : 47, "classmate" : 3 } { "_id" : ObjectId("5c835973043334857a7dbe86"), "classmate" : 4, "sc" : "bbb" } >

條件關鍵字

mongodb的條件查詢與普通的SQL查詢不一樣，使用特定的符號來代替，下面表格的常用的的條件代替。

操作格式范例RDBMS中的類似語句

等于	{<key>:<value>}	db.col.find({"by":"aaa"}).pretty()	where by = 'aaa'
小于	{<key>:{$lt:<value>}}	db.col.find({"likes":{$lt:50}}).pretty()	where likes < 50
小于或等于	{<key>:{$lte:<value>}}	db.col.find({"likes":{$lte:50}}).pretty()	where likes <= 50
大于	{<key>:{$gt:<value>}}	db.col.find({"likes":{$gt:50}}).pretty()	where likes > 50
大于或等于	{<key>:{$gte:<value>}}	db.col.find({"likes":{$gte:50}}).pretty()	where likes >= 50
不等于	{<key>:{$ne:<value>}}	db.col.find({"likes":{$ne:50}}).pretty()	where likes != 50

?

條件查詢實例

1: 基礎查詢 where的練習:查出滿足以下條件的商品 1.1:主鍵為32的商品db.goods.find({goods_id:32});1.2:不屬第3欄目的所有商品($ne)db.goods.find({cat_id:{$ne:3}},{goods_id:1,cat_id:1,goods_name:1});1.3:本店價格高于3000元的商品{$gt} db.goods.find({shop_price:{$gt:3000}},{goods_name:1,shop_price:1}); 1.4:本店價格低于或等于100元的商品($lte) db.goods.find({shop_price:{$lte:100}},{goods_name:1,shop_price:1}); 1.5:取出第4欄目或第11欄目的商品($in) db.goods.find({cat_id:{$in:[4,11]}},{goods_name:1,shop_price:1}); 1.6:取出100<=價格<=500的商品($and) db.goods.find({$and:[{price:{$gt:100},{$price:{$lt:500}}}]);
和下面方式結果一樣：
db.goods.find({shop_price:{$gt:100}, shop_price:{$lt:5000}}, {goods_name:1, _id:0, goods_number:1, shop_price:1}) 1.7:取出不屬于第3欄目且不屬于第11欄目的商品($and $nin和$nor分別實現) db.goods.find({$and:[{cat_id:{$ne:3}},{cat_id:{$ne:11}}]},{goods_name:1,cat_id:1}) db.goods.find({cat_id:{$nin:[3,11]}},{goods_name:1,cat_id:1}); db.goods.find({$nor:[{cat_id:3},{cat_id:11}]},{goods_name:1,cat_id:1}); 1.8:取出價格大于100且小于300,或者大于4000且小于5000的商品() db.goods.find({$or:[{$and:[{shop_price:{$gt:100}},{shop_price:{$lt:300}}]},{$and:[{shop_price:{$gt:4000}},{shop_price:{$lt:5000}}]}]},{goods_name:1,shop_price:1}); 1.9:取出goods_id%5 == 1, 即,1,6,11,..這樣的商品 db.goods.find({goods_id:{$mod:[5,1]}}); 1.10:取出有age屬性的文檔 db.stu.find({age:{$exists:1}}); 含有age屬性的文檔將會被查出

1.11：使用where進行查詢：
db.stu.find({$where:'this.goods_id>=3'}); // value直接接過濾條件

游標?cursor

游標不是查詢結果，而是查詢的返回資源，或者接口。類似與python中的生成器

通過調用可以逐條讀取。直接將查詢結果賦值給一個變量就是游標

var cursor = db.colllections_name.find(query, projection) cursor.hasNext() //判斷是否已經取完 cursor.Next() // 取出下一個元素

通常情況下我們用循環來獲取游標中的值：

while循環

> var cursor=db.goods.find(); > while(cursor.hasNext()){ ... printjson(cursor.next());} {

for循環

> var cursor=db.goods.find(); > for(var doc=true;cursor.hasNext();){printjson(cursor.next())}

? > for(var cursor=db.goods.find(); doc=true;cursor.hasNext()){printjson(cursor.next())}

forEach循環：可以自己添加回調函數

> var fun = function(obj){print(obj.goods_name)}; // 定義函數 > var cursor = db.goods.find(); // 創建游標 > cursor.forEach(fun); // 調用函數

游標分頁：這個默認形式，也可以使用游標的形式

db.collection_name.find().skip(10); //表示跳過10開始取
db.collection_name.find().limit(10); //表示取10個

?索引

? ? 索引提高查詢速度，但會降低寫入速度，所以再使用的時候需要權衡查詢字段，不必在太多列上創建索引。在Mongodb中，索引可以按字段升序/降序來創建索引，便于排序。默認情況下mongodb是用btree來組織索引文件，2.4后也有通過hash來創建索引。

查看當前文檔有那些索引

>db.collection_name.getIndexes()

創建普通索引(1表示升序，-1表示降序)

> db.collection_name.ensureIndex({field:1})

創建多列索引

> db.collection_name.ensureIndex({field1:1, field2:1});

創建唯一索引

> db.collection_name.ensureIndex({field:1},{unique:true});

創建hash索引

> db.collection_name.ensureIndex({field:'hashed'});

創建稀疏索引：如果針對field做索引，針對不含field列的文檔將不做索引。而普通索引是會把該列作為null表示，并建立索引。

> db.collection_name.ensureIndex({name:1}, {sparse:true});

重建索引

一個表經過很多次修改后，導致表的文件產生空洞，索引文件也是如此，可以通過索引重建，減少索引文件碎片，并提高索引的效率。類似mysql中的?optimize table

> db.collection_name.reIndex();

?

轉載于:https://www.cnblogs.com/tashanzhishi/p/10491890.html

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