查看當前數據庫
db
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查看所有數據庫
show dbs / show databases
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切換數據庫
use db_name
# 注意
use 如果後面數據庫不存在,會自動創建
但此時,show dbs 查詢不到
插入數據後方可查詢到
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刪除當前的數據庫
db.dropDatabase()
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手動創建集合
db.createCollection(name,optons)
db.createCollection("str")
db.createCollection("sub",{cappec:true,size:10})
參數:capped:默認值爲false表示不設置上限,值爲true表示設置上限
參數size: 當capped爲true時,需要設置此參數,表示上限大小,當文檔到上限時,會將之前數據覆蓋,單位爲字節
查看集合 show collections
刪除集合 db.集合名稱.drop()
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Mongodb 存儲數據類型
string : 字符串
Boolean:存儲一個布爾值
lnterger :整數 32位或64位
Double:存儲浮點值
Arrays:數組或列表,多個值存儲到一個鍵
object:用於嵌入式文檔,即一個值爲一個文檔
Null : 存儲一個空值
Timestamp:表示從1970-1-1到現在的秒數
Date:存儲當前日期或時間的unix時間格式
objectID 12字節的十六進制的數
前4個字節:時間戳
接下來3個字節:機器ID
接下來2個字節中Mongodb服務進程ID
最後三個字節簡單的增量值
> show dbs
admin (empty)
local 0.078GB
zml 0.078GB
> use zml
switched to db zml
> db.createCollection("test1")
{ "ok" : 1 }
> db.test1.insert({"name":"zhangsan"})
WriteResult({ "nInserted" : 1 })
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
> db.test1.insert({_id:11111,name:"wanger",age:"12"})
WriteResult({ "nInserted" : 1 })
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
{ "_id" : 11111, "name" : "wanger", "age" : "12" }
> db.test1.insert({_id:11111,name:"wanger",age:"12"})
WriteResult({
"nInserted" : 0,
"writeError" : {
"code" : 11000,
"errmsg" : "insertDocument :: caused by :: 11000 E11000 duplicate key error index: zml.test1.$_id_ dup key: { : 11111.0 }"
}
})
> db.test1.save({_id:11111,name:"wanger",age:"12"})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
{ "_id" : 11111, "name" : "wanger", "age" : "12" }
> db.test1.save({_id:11111,name:"wanger",age:"13"})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
{ "_id" : 11111, "name" : "wanger", "age" : "13" }
總結:db.集合名稱.insert({}) 插入數據,沒有輸入ID就自動創建ID,有ID就按輸入的ID,如果ID已存在就報錯
db.集合名稱.save({}),輸入相同的ID,則更新數據,不是存在的ID,則想當於插入數據
更新數據
db.集合名稱.update(<query>,<update>,{multi:<boolean>})
參數query:查詢條件
參數update:更新操作符
參數multi:可選,默認是false,表示只更新找到的第一條記錄
值爲true表示把滿足條件的文檔全部更新
db.stu.update({name:hr}),{name:mnc} ) 更新一條
db.stu.update({name:hr}),{$set:{name:mnc} }) 更新一條
db.stu.update({name:hr}),{$set:{name:mnc}},{multi:true}) 更新一條
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
{ "_id" : 11111, "name" : "wanger", "age" : "13" }
{ "_id" : 11110, "name" : "wanger", "age" : "13" }
> db.test1.update({"name":"wanger"},{"name":"lisi"})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
{ "_id" : 11111, "name" : "lisi" }
{ "_id" : 11110, "name" : "wanger", "age" : "13" }
> db.test1.update({"name":"wanger"},{$set:{"name":"lisi"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
{ "_id" : 11111, "name" : "lisi" }
{ "_id" : 11110, "name" : "lisi", "age" : "13" }
刪除操作
db.集合名稱.remove(<query>,{justOne:<boolean>})
參數query:可選,刪除的文檔條件
參數justOne:可選,如果設爲true或1,則只刪除一條,默認爲false,表示刪除多條
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
{ "_id" : 11111, "name" : "lisi" }
{ "_id" : 11110, "name" : "lisi", "age" : "13" }
{ "_id" : ObjectId("5f01ddb5b17ac23a4b796ba0"), "name" : "wanger", "age" : 12 }
{ "_id" : ObjectId("5f01ddbcb17ac23a4b796ba1"), "name" : "wangsan", "age" : 12 }
{ "_id" : ObjectId("5f01ddc5b17ac23a4b796ba2"), "name" : "wangsan", "age" : 14 }
{ "_id" : ObjectId("5f01ddc8b17ac23a4b796ba3"), "name" : "wangsan", "age" : 15 }
> db.test1.remove({name:"wangsan"},{justOne:true})
WriteResult({ "nRemoved" : 1 })
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
{ "_id" : 11111, "name" : "lisi" }
{ "_id" : 11110, "name" : "lisi", "age" : "13" }
{ "_id" : ObjectId("5f01ddb5b17ac23a4b796ba0"), "name" : "wanger", "age" : 12 }
{ "_id" : ObjectId("5f01ddc5b17ac23a4b796ba2"), "name" : "wangsan", "age" : 14 }
{ "_id" : ObjectId("5f01ddc8b17ac23a4b796ba3"), "name" : "wangsan", "age" : 15 }
> db.test1.remove({name:"wangsan"})
WriteResult({ "nRemoved" : 2 })
> db.test1.find()
{ "_id" : ObjectId("5f01d623b17ac23a4b796b9f"), "name" : "zhangsan" }
{ "_id" : 11111, "name" : "lisi" }
{ "_id" : 11110, "name" : "lisi", "age" : "13" }
{ "_id" : ObjectId("5f01ddb5b17ac23a4b796ba0"), "name" : "wanger", "age" : 12 }