---
title: "Mongodb备忘录"
date: 2019-09-23T10:18:30+08:00
draft: false
toc: true
images:
tags: [database]
categories: server
---

- 创建唯一索引

  ```javascript
  // 删除重复key
  db.games2.aggregate([
      {
          "$group": {
              "_id": "$game_id",
              "dups": {
                  "$push": "$_id"
              },
              "count": {
                  "$sum": 1
              }
          }
      },
      {
          "$match": {
              "count": {
                  "$gt": 1
              }
          }
      }
  ]).forEach(function(doc) {
      doc.dups.shift();
      db.games2.remove({
          "_id": {
              "$in": doc.dups
          }
      });
  });
  
  // 创建索引
  db.games2.createIndex({"game_id": 1}, {unique: true});
  ```


- 查找具有相同字段值的文档

  ```javascript
  db.games2.find({$where: "this.fileId == this.fileUid"});
  ```


- 创建管理员用户

  ```javascript
  use admin
  db.createUser({
      user: "username",
      pwd: "password",
      roles: ["root"]
  })
  
  db.createUser({
      user: "myUserAdmin",
      pwd: passwordPrompt(), // or cleartext password
      roles: [ { role: "userAdminAnyDatabase", db: "admin" }, "readWriteAnyDatabase" ]
    }
  )
  ```

- 创建数据库用户

  ```javascript
  use mydb
  db.createUser({
      user: "myTester",
      pwd:  passwordPrompt(),   // or cleartext password
      roles: [ { role: "readWrite", db: "mydb" },
               { role: "read", db: "reporting" } ]
    }
  )
  ```

- 连接数据库

  ```javascript
  mongo --port 27017 -u "myTester" --authenticationDatabase "mydb" -p
  ```