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NSD NOSQL DAY05

1 案例1：配置MongoDB副本集

1.1 問題

• 具體要求：
• 準備3臺mongodb伺服器
• 配置副本集服務
• 驗證副本集配置

1.2 方案

準備三臺虛擬機器，配置mongodb副本集，ip分別為192.158.4.51， 192.168.4.52，192.168.4.53其中一個是主節點，負責處理客戶端請求，其餘的都是從節點，負責複製主節點上的資料，實現儲存資料副本，提高了資料的可用性，具體分配如表-1所示：

表-1

1.3 步驟

實現此案例需要按照如下步驟進行。

步驟一：建立mongodb副本集

1）三臺主機安裝mongodb（以4.51為例）

1. [[email protected] ~]# cd mongodb/
2. [[email protected] mongodb]# mkdir /usr/local/mongodb
3. [[email protected] mongodb]# cd /usr/local/mongodb
4. [[email protected] mongodb]# cp -r \
5. /root/mongodb/mongodb-linux-x86_64-rhel70-3.6.3/bin/ .
6. [[email protected] mongodb]# ls
7. bin
8. [[email protected]
   mongodb]# mkdir etc
9. [[email protected] mongodb]# mkdir log
10. [[email protected] mongodb]# mkdir -p data/db
11. [[email protected] mongodb]# vim etc/mongodb.conf
12. dbpath=/usr/local/mongodb/data/db/
13. logpath=/usr/local/mongodb/log/mongodb.log
14. logappend=true
15. fork=true
16. bind_ip=192.168.4.51
17. port=27077
18. replSet=rs1        
19. //加入到副本集，rs1名字隨便起，想知道誰和我在一個副本集裡，三臺機器的名字一樣,都寫rs1

2）設定PATH變數

1. [[email protected] mongodb]# vim /etc/profile
2. export PATH=/usr/local/mongodb/bin:$PATH
3. [[email protected] mongodb]# source /etc/profile

3）由於啟動和停止服務名字太長，可以起一個別名

給停止服務起一個別名

1. [[email protected] mongodb]# alias cmdb='mongod --dbpath=/usr/local/mongodb/data/db/ --shutdown'

給啟動服務起一個別名

1. [[email protected] mongodb]# alias smdb='mongod -f /usr/local/mongodb/etc/mongodb.conf'

4）啟動服務並連線

1. [[email protected] ~]# smdb
2. about to fork child process, waiting until server is ready for connections.
3. forked process: 5656
4. child process started successfully, parent exiting
5. [[email protected] ~]# mongo --host 192.168.4.51 --port 27077
6. MongoDB shell version v3.6.3
7. connecting to: mongodb://192.168.4.51:27077/
8. MongoDB server version: 3.6.3
9. ...
10. >

5）配置叢集資訊，任意一臺都可以，在這裡在51上面操作

1. > rs1_config = {        //rs1_config隨便起變數名,要記住
2. _id:"rs1",         //必須為rs1這個，三臺主機叢集名，配置檔案裡面寫的是這個
3. members:[
4. {_id:0,host:"192.168.4.51:27077"},        //_id值隨意，host值固定
5. {_id:1,host:"192.168.4.52:27078"},
6. {_id:2,host:"192.168.4.53:27079"}
7. ]
8. };        //回車，出現下面情況為成功
9. {
10.     "_id" : "rs1",
11.     "members" : [
12.         {
13.             "_id" : 0,
14.             "host" : "192.168.4.51:27077"
15.         },
16.         {
17.             "_id" : 1,
18.             "host" : "192.168.4.52:27078"
19.         },
20.         {
21.             "_id" : 2,
22.             "host" : "192.168.4.53:27079"
23.         }
24.     ]
25. }
26. >

6）初始化Replica Sets環境

1. > rs.initiate(rs1_config)
2. {
3.     "ok" : 1,
4.     "operationTime" : Timestamp(1538187475, 1),
5.     "$clusterTime" : {
6.         "clusterTime" : Timestamp(1538187475, 1),
7.         "signature" : {
8.             "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
9.             "keyId" : NumberLong(0)
10.         }
11.     }
12. }
13. rs1:SECONDARY>
14. rs1:PRIMARY>            //提示PRIMARY，51為主

7）在52和53上面檢視

1. [[email protected] ~]# mongo --host 192.168.4.52 --port 27078
2. MongoDB shell version v3.6.3
3. connecting to: mongodb://192.168.4.52:27078/
4. MongoDB server version: 3.6.3
5. ...
6. ...
7. rs1:SECONDARY>         //提示SECONDARY，52為從
8. rs1:SECONDARY>
9. rs1:SECONDARY>
10. [[email protected] ~]# mongo --host 192.168.4.53 --port 27079
11. MongoDB shell version v3.6.3
12. connecting to: mongodb://192.168.4.53:27079/
13. MongoDB server version: 3.6.3
14. ...
15. ...
16. rs1:SECONDARY>     //提示SECONDARY，53為從
17. rs1:SECONDARY>

注意：如果初始化錯誤，重啟服務登陸之後重新設定變數，之後再重新初始化

8）檢視狀態資訊

1. rs1:PRIMARY> rs.status()
2. ...
3.     "members" : [
4.         {
5.             "_id" : 0,
6.             "name" : "192.168.4.51:27077",
7.             "health" : 1,
8.             "state" : 1,
9.             "stateStr" : "PRIMARY",
10.             "uptime" : 2295,
11.             ...
12. ...
13.         },
14.         {
15.             "_id" : 1,
16.             "name" : "192.168.4.52:27078",
17.             "health" : 1,
18.             "state" : 2,
19.             "stateStr" : "SECONDARY",
20.             "uptime" : 384,
21.             ...
22. ...
23.         },
24.         {
25.             "_id" : 2,
26.             "name" : "192.168.4.53:27079",
27.             "health" : 1,
28.             "state" : 2,
29.             "stateStr" : "SECONDARY",
30. ...
31. ...

9）檢視是否是master庫

1. rs1:PRIMARY> rs .isMaster( )
2. {
3.     "hosts" : [
4.         "192.168.4.51:27077",
5.         "192.168.4.52:27078",
6.         "192.168.4.53:27079"
7.     ],
8.     "setName" : "rs1",
9.     "setVersion" : 1,
10.     "ismaster" : true,        //主庫
11.     "secondary" : false,
12.     "primary" : "192.168.4.51:27077",
13.     "me" : "192.168.4.51:27077",
14. ...
15. ...

10）驗證副本集，同步資料驗證（51上面寫資料）

1. rs1:PRIMARY> use gamedb2
2. switched to db gamedb2
3. rs1:PRIMARY> db.a.save({name:"yaya",age:75,em:"[email protected]"})
4. WriteResult({ "nInserted" : 1 })

52上面檢視

1. [[email protected] ~]# mongo --host 192.168.4.52 --port 27078
2. rs1:SECONDARY> db.getMongo().setSlaveOk()
3. rs1:SECONDARY> show dbs        //有gamedb2庫
4. admin 0.000GB
5. config 0.000GB
6. ddsdb 0.000GB
7. gamedb2 0.000GB
8. local 0.000GB
9. test 0.000GB

步驟三：切換主庫驗證

1）自動切換主庫驗證

關閉51

1. [[email protected] ~]# cmdb        //之前設定的別名
2. killing process with pid: 5656

檢視52和53

1. [[email protected] ~]# mongo --host 192.168.4.52 --port 27078
2. MongoDB shell version v3.6.3
3. connecting to: mongodb://192.168.4.52:27078/
4. MongoDB server version: 3.6.3
5. ...
6. ...
7. rs1:PRIMARY>         //52為主
8. rs1:PRIMARY>
9. [[email protected] ~]# mongo --host 192.168.4.53 --port 27079
10. MongoDB shell version v3.6.3
11. connecting to: mongodb://192.168.4.53:27079/
12. MongoDB server version: 3.6.3
13. ...
14. ...
15. rs1:SECONDARY>        //53為從

啟動51，啟動後不會再變為主，會成為52的從

1. [[email protected] ~]# smdb
2. about to fork child process, waiting until server is ready for connections.
3. forked process: 6598
4. child process started successfully, parent exiting
5. rs1:SECONDARY> rs.isMaster()
6. {
7.     "hosts" : [
8.         "192.168.4.51:27077",
9.         "192.168.4.52:27078",
10.         "192.168.4.53:27079"
11.     ],
12.     "setName" : "rs1",
13.     "setVersion" : 1,
14.     "ismaster" : false,
15.     "secondary" : true,
16.     "primary" : "192.168.4.52:27078",
17.     "me" : "192.168.4.51:27077",
18. ...

2 案例2：文件管理

2.1 問題

• 基於MongoDB環境完成下列練習：
• 插入文件
• 查詢文件
• 更新文件
• 刪除文件

2.2 步驟

實現此案例需要按照如下步驟進行。

步驟一：管理文件

1）把系統使用者資訊/etc/passwd儲存到mdb庫下的user集合裡

1. rs1:PRIMARY> use mdb
2. switched to db mdb
3. rs1:PRIMARY> db.user.save({name:"yaya",password:"x",uid:9999,gid:9999,comment:"",homdir:"/home",shell:"/bin/bash"})
4. WriteResult({ "nInserted" : 1 })
5. rs1:PRIMARY> exit
6. bye
7. [[email protected] ~]# mongoexport --host 192.168.4.52 --port 27078 -d mdb -c user -f name,password,uid,gid,comment,homdir,shell --type=csv -o /tmp/user.csv
8. 2018-09-29T11:04:14.967+0800    connected to: 192.168.4.52:27078
9. 2018-09-29T11:04:14.968+0800    exported 1 record
10. [[email protected] ~]# cp /etc/passwd /tmp
11. [[email protected] ~]# sed -i 's/:/,/g' /tmp/passwd
12. [[email protected] ~]# sed -i '$r /tmp/passwd' /tmp/user.csv
13. [[email protected] ~]# mongoimport --host 192.168.4.52 --port 27078 -d mdb -c user --headerline --type=csv /tmp/user.csv
14. 2018-09-29T11:06:08.355+0800    connected to: 192.168.4.52:27078
15. 2018-09-29T11:06:08.363+0800    imported 41 documents

2）檢視

1. [[email protected] ~]# mongo --host 192.168.4.52 --port 27078
2. rs1:PRIMARY> use mdb
3. switched to db mdb
4. rs1:PRIMARY> db.user.findOne()
5. {
6.     "_id" : ObjectId("5baeeb37ce3cc5539aa21f38"),
7.     "name" : "yaya",
8.     "password" : "x",
9.     "uid" : 9999,
10.     "gid" : 9999,
11.     "comment" : "",
12.     "homdir" : "/home",
13.     "shell" : "/bin/bash"
14. }

db.user.find（{條件},{定義顯示的欄位}） #指定查詢條件並指定顯示的欄位

1. rs1:PRIMARY> db.user.find()
2. { "_id" : ObjectId("5baeeb37ce3cc5539aa21f38"), "name" : "yaya", "password" : "x", "uid" : 9999, "gid" : 9999, "comment" : "", "homdir" : "/home", "shell" : "/bin/bash" }
3. ...
4. Type "it" for more            //出現這個按it，默認出現20行

檢視每行的name欄位

1. rs1:PRIMARY> db.user.find({},{name:1})        
2. { "_id" : ObjectId("5baeeb37ce3cc5539aa21f38"), "name" : "yaya" }
3. ...
4. ...
5. { "_id" : ObjectId("5baeec2001805180a1011843"), "name" : "rpc" }
6. Type "it" for more

不看_id欄位

1. rs1:PRIMARY> db.user.find({},{_id:0})
2. { "name" : "yaya", "password" : "x", "uid" : 9999, "gid" : 9999, "comment" : "", "homdir" : "/home", "shell" : "/bin/bash" }
3. ...
4. ...
5. { "name" : "rpc", "password" : "x", "uid" : 32, "gid" : 32, "comment" : "Rpcbind Daemon", "homdir" : "/var/lib/rpcbind", "shell" : "/sbin/nologin" }
6. Type "it" for more

不看_id那一列，看name那一列

1. rs1:PRIMARY> db.user.find({},{_id:0,name:1})
2. { "name" : "yaya" }
3. ...
4. ...
5. { "name" : "rpc" }
6. Type "it" for more

檢視以a開頭的name欄位

1. rs1:PRIMARY> db.user.find({name:/^a/},{_id:0})
2. { "name" : "adm", "password" : "x", "uid" : 3, "gid" : 4, "comment" : "adm", "homdir" : "/var/adm", "shell" : "/sbin/nologin" }
3. { "name" : "abrt", "password" : "x", "uid" : 173, "gid" : 173, "comment" : "", "homdir" : "/etc/abrt", "shell" : "/sbin/nologin" }
4. { "name" : "avahi", "password" : "x", "uid" : 70, "gid" : 70, "comment" : "Avahi mDNS/DNS-SD Stack", "homdir" : "/var/run/avahi-daemon", "shell" : "/sbin/nologin" }

顯示查詢結果的前一行

limit 數字

1. rs1:PRIMARY> db.user.find({name:/^a/},{_id:0}).limit (1)
2. { "name" : "adm", "password" : "x", "uid" : 3, "gid" : 4, "comment" : "adm", "homdir" : "/var/adm", "shell" : "/sbin/nologin" }

顯示name欄位以a開頭的第一行

1. rs1:PRIMARY> db.user.findOne({name:/^a/},{_id:0,name:1,shell:1,uid:1})
2. { "name" : "adm", "uid" : 3, "shell" : "/sbin/nologin" }

跳過幾行顯示 （2行）

skip 數字

1. rs1:PRIMARY> db.user.find({name:/^a/},{_id:0,name:1,shell:1}).skip (2)
2. { "name" : "avahi", "shell" : "/sbin/nologin" }

預設升序排序

sort 欄位名

1. rs1:PRIMARY> db.user.find({name:/^a/},{_id:0,name:1,shell:1,uid:1}).sort({uid:1})
2. { "name" : "adm", "uid" : 3, "shell" : "/sbin/nologin" }
3. { "name" : "avahi", "uid" : 70, "shell" : "/sbin/nologin" }
4. { "name" : "abrt", "uid" : 173, "shell" : "/sbin/nologin" }

降序排序

1. rs1:PRIMARY> db.user.find({name:/^a/},{_id:0,name:1,shell:1,uid:1}).sort({uid:-1})
2. { "name" : "abrt", "uid" : 173, "shell" : "/sbin/nologin" }
3. { "name" : "avahi", "uid" : 70, "shell" : "/sbin/nologin" }
4. { "name" : "adm", "uid" : 3, "shell" : "/sbin/nologin" }

顯示name欄位以a開頭和uid為3的所有行

1. rs1:PRIMARY> db.user.find({name:/^a/,uid:3},{_id:0,name:1,shell:1,uid:1})
2. { "name" : "adm", "uid" : 3, "shell" : "/sbin/nologin" }

3）條件判斷的表示方式

$in 在...裡

1. rs1:PRIMARY> db.user.find({uid:{$in:[1,6,9]}})        //uid的為1或者6或者9的匹配
2. { "_id" : ObjectId("5baeec2001805180a1011833"), "name" : "bin", "password" : "x", "uid" : 1, "gid" : 1, "comment" : "bin", "homdir" : "/bin", "shell" : "/sbin/nologin" }
3. { "_id" : ObjectId("5baeec2001805180a1011838"), "name" : "shutdown", "password" : "x", "uid" : 6, "gid" : 0, "comment" : "shutdown", "homdir" : "/sbin", "shell" : "/sbin/shutdown" }

$nin 不在...裡

1. rs1:PRIMARY> db.user.find({uid:{$nin:[1,6,9]}},{_id:0,name:1,uid:1})
2. { "name" : "yaya", "uid" : 9999 }
3. ...
4. ...
5. { "name" : "saslauth", "uid" : 996 }
6. Type "it" for more

$or 條件滿足任意其中一個即可

1. rs1:PRIMARY> db.user.find({$or:[{name:"root"},{uid:1}]},{_id:0,name:1,uid:1})
2. { "name" : "root", "uid" : 0 }
3. { "name" : "bin", "uid" : 1 }

4）正則匹配，以a開頭的name欄位

1. rs1:PRIMARY> db.user.find({name:/^a/},{_id:0,name:1,uid:1})
2. { "name" : "adm", "uid" : 3 }
3. { "name" : "abrt", "uid" : 173 }
4. { "name" : "avahi", "uid" : 70 }

5）數值比較

$lt(小於) $lte（小於等於） $gt（大於） $gte（大於等於） $ne（不等於）

1. rs1:PRIMARY> db.user.find({uid:{$gte:10,$lte:40}},{_id:0,name:1,uid:1})
2. { "name" : "operator", "uid" : 11 }
3. { "name" : "games", "uid" : 12 }
4. { "name" : "ftp", "uid" : 14 }
5. { "name" : "rpc", "uid" : 32 }
6. { "name" : "rpcuser", "uid" : 29 }
7. { "name" : "ntp", "uid" : 38 }

匹配null：可以匹配沒有的欄位，也可以檢查這個欄位有沒有

1. rs1:PRIMARY> db.user.save({name:null,uid:null})
2. WriteResult({ "nInserted" : 1 })
3. rs1:PRIMARY> db.user.find({name:null})
4. { "_id" : ObjectId("5baef385f9f3bf625ea1dbd6"), "name" : null, "uid" : null }
5. rs1:PRIMARY> db.user.find({shell:null})    //表示此條文件沒有shell欄位
6. { "_id" : ObjectId("5baef385f9f3bf625ea1dbd6"), "name" : null, "uid" : null }
7. rs1:PRIMARY>

6）save和insert的區別

相同點：當集合不存在時建立集合，並插入記錄

不同點：save() _id欄位值已經存在時，修改文件欄位值

insert() _id欄位值已經存在時，放棄修改文件欄位值

1. rs1:PRIMARY> db.t1.save({name:"bob",age:19})
2. WriteResult({ "nInserted" : 1 })
3. rs1:PRIMARY> db.t1.insert({name:"bob",age:19})
4. WriteResult({ "nInserted" : 1 })
5. rs1:PRIMARY> db.t1.save({_id:7,name:"bob",age:19})
6. WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : 7 })
7. rs1:PRIMARY> db.t1.find()
8. ...
9. ...
10. { "_id" : 7, "name" : "bob", "age" : 19 }
11. rs1:PRIMARY> db.t1.save({_id:7,name:"tom",age:19})        //把上一條的記錄直接修改
12. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
13. rs1:PRIMARY> db.t1.find()
14. ...
15. ...
16. { "_id" : 7, "name" : "tom", "age" : 19 }
17. rs1:PRIMARY>
18. rs1:PRIMARY>
19. rs1:PRIMARY> db.t1.insert({_id:8,name:"tom",age:19})        //可以存上
20. WriteResult({ "nInserted" : 1 })
21. rs1:PRIMARY> db.t1.insert({_id:8,name:"tom",age:19})        //存不上
22. WriteResult({
23.     "nInserted" : 0,
24.     "writeError" : {
25.         "code" : 11000,
26.         "errmsg" : "E11000 duplicate key error collection: mdb.t1 index: _id_ dup key: { : 8.0 }"
27.     }
28. })

7）插入多行文件

1. rs1:PRIMARY> db.t1.insertMany([{name:"xiaojiu"},{name:"laoshi"}])
2. {
3.     "acknowledged" : true,
4.     "insertedIds" : [
5.         ObjectId("5baef526f9f3bf625ea1dbd9"),
6.         ObjectId("5baef526f9f3bf625ea1dbda")
7.     ]
8. }
9. rs1:PRIMARY> db.t1.find()
10. ...
11. ...
12. { "_id" : ObjectId("5baef526f9f3bf625ea1dbd9"), "name" : "xiaojiu" }
13. { "_id" : ObjectId("5baef526f9f3bf625ea1dbda"), "name" : "laoshi" }

8）update修改

1. rs1:PRIMARY> db.user.update({name:"root"},{password:"XXX"})
2. //如果這一列不寫完整，這一行除了password這一行，這一列的其他值都沒有了相當於刪除（要寫完整）
3. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
4. rs1:PRIMARY> db.t1.find({name:"root"})
5. rs1:PRIMARY> db.user.find({name:"root"}) //沒有東西，除了password:"XXX"

9）$set 條件匹配時，修改指定欄位的值(區域性修改)

1. rs1:PRIMARY> db.user.update({name:"adm"},{$set:{password:"AAA"}})
2. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
3. rs1:PRIMARY> db.user.find({name:"adm"})        //還存在
4. { "_id" : ObjectId("5baeec2001805180a1011835"), "name" : "adm", "password" : "AAA", "uid" : 3, "gid" : 4, "comment" : "adm", "homdir" : "/var/adm", "shell" : "/sbin/nologin" }
5. rs1:PRIMARY> db.user.update({name:/^r/},{$set:{password:"FFF"}})        
6. //預設修改匹配條件的第一行
7. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })    
8. rs1:PRIMARY> db.user.update({name:/^a/},{$set:{password:"FFF"}},false,true)
9. //改匹配到的所有
10. WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })

10）$unset 刪除與條件匹配文件的欄位

1. rs1:PRIMARY> db.user.update({name:"sync"},{$unset:{password:1}})     
2. //刪除password欄位
3. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

11）陣列

1. rs1:PRIMARY> db.user.insert({name:"bob",like:["a","b","c","d","e","f",]})
2. WriteResult({ "nInserted" : 1 })

$pop 刪除陣列末尾一個元素，1刪除最後一個，-1刪除第一個

1. rs1:PRIMARY> db.user.update({name:"bob"},{$pop:{like:1}})    
2. //刪除匹配的第一條的最後一個
3. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
4. rs1:PRIMARY> db.user.update({name:"bob"},{$pop:{like:-1}})    
5. //刪除匹配的第一條的第一個
6. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

$push 向陣列中新增新元素

1. rs1:PRIMARY> db.user.update({name:"bob"},{$push:{like:"Z"}})        //預設新增到最後
2. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
3. rs1:PRIMARY> db.user.update({name:"bob"},{$push:{like:"W"}})
4. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
5. rs1:PRIMARY> db.user.find({name:"bob"})
6. { "_id" : ObjectId("5baef7b2034891a205de2959"), "name" : "bob", "like" : [ "b", "c", "d", "e", "Z", "W" ] }

$addToSet 避免重複新增

1. rs1:PRIMARY> db.user.update({name:"bob"},{$addToSet:{like:"W"}})
2. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
3. rs1:PRIMARY> db.user.find({name:"bob"})
4. { "_id" : ObjectId("5baef7b2034891a205de2959"), "name" : "bob", "like" : [ "b", "c", "d", "e", "Z", "W" ] }

$pull 刪除數組裡的指定元素，若有兩個bob可以用_id值定義把name:"bob"換成id值

1. rs1:PRIMARY> db.user.update({name:"bob"},{$pull:{like:"c"}})
2. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
3. rs1:PRIMARY> db.user.find({name:"bob"})
4. { "_id" : ObjectId("5baef7b2034891a205de2959"), "name" : "bob", "like" : [ "b", "d", "e", "Z", "W" ] }
5. rs1:PRIMARY> db.user.update({"_id":ObjectId("5afc1a717eff45e9cfc57ed3")},{$push:{like:"S"}})
6. WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
7. rs1:PRIMARY>

$inc 條件匹配時，欄位值自加或自減

1. rs1:PRIMARY> db.user.update({uid:{$lte:10}},{$inc:{uid:2}})         
2. //設定欄位值自加2,預設改第一行
3. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
4. rs1:PRIMARY> db.user.update({uid:{$lte:10}},{$inc:{uid:2}},false,true)    
5. //設定欄位值自加2，false,true改全部
6. WriteResult({ "nMatched" : 8, "nUpserted" : 0, "nModified" : 8 })
7. rs1:PRIMARY>
8. rs1:PRIMARY> db.user.update({uid:{$lte:10}},{$inc:{uid:-1}})
9. //負數時是自減1，預設改第一行
10. WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

12）刪除文件

remove()與drop()的區別

remove()刪除文件時不刪除索引

drop()刪除集合的時候同時刪除索引

1. rs1:PRIMARY> db.t1.remove({})
2. WriteResult({ "nRemoved" : 6 })
3. rs1:PRIMARY> db.user.remove({name:"/^a/"})        //刪除以a開頭的記錄
4. WriteResult({ "nRemoved" : 0 })
5. rs1:PRIMARY> db.t1.drop()        //刪除集合t1
6. true
7. rs1:PRIMARY>