MongoDB 基本使用

文章目录

• 起步
• 安装
• 启动

小试牛刀

• 查看数据库
• 创建/进入数据库
• 查看当前数据库
• 插入文档
• 查看文档
• 查看当前数据库的所有集合
• 删除文档
• 删除集合
• 删除当前数据库

更新 update(query, update, upsert, multi)

• $inc 增加计数
• \$set 设置字段值（若不存在则创建，已存在则覆盖），\$unset 删除字段
• $push 对数组追加元素
• $pop 从数组元素中弹出元素（1 从尾部，-1 从头部）
• $addToSet 添加到集合中（若已存在则不会增加）
• $pull 删除数组中完全匹配的元素
• $set 的补充说明：对数组中的某个位置元素进行更新
• update 第三个参数 upsert（是否在不存在的情况下进行插入）
• save() 更新或创建（更新时需要指定 _id）
• update 第四个参数是否更新多个文档（默认只更新找到的第一个文档）

查询 find(query, show_fields)

参考

起步

安装

brew install mongodb

# 遇到 Error: An unexpected error occurred during the `brew link` step 解决方法
# 参考 https://blog.csdn.net/qq_24909089/article/details/83378210
sudo mkdir /usr/local/Frameworks
sudo chown -R $(whoami) /usr/local/Frameworks

启动

# 启动服务器
mkdir -p ./mongodb/data/db
mongod --dbpath ./mongodb/data/db

# 启动客户端
mongo

小试牛刀

查看数据库

show dbs

admin 0.000GB
config 0.000GB
local 0.000GB

创建/进入数据库

use test

switched to db test

查看当前数据库

db

test

插入文档

db.myCollection.insert({‘fruit’: ‘apple’})

WriteResult({ "nInserted" : 1 })

查看文档

db.myCollection.find()

{ "_id" : ObjectId("5cd6931cb2978f4bd9becafc"), "fruit" : "apple" }

查看当前数据库的所有集合

show tables 或 show collections

myCollection

删除文档

db.myCollection.remove()

WriteResult({ "nRemoved" : 1 })

删除集合

db.myCollection.drop()

true

删除当前数据库

db.dropDatabase()

{ "dropped" : "test", "ok" : 1 }

更新 update(query, update, upsert, multi)

$inc 增加计数

数据准备
db.myCollection.insert({“fruit”: “banana”, “count”: 1})

增加 3
db.myCollection.update({“fruit”: “banana”}, {$inc: {“count”: 3}})
db.myCollection.find()

# 由 1 变成 4
{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4 }

$set 设置字段值（若不存在则创建，已存在则覆盖），$unset 删除字段

增加字段 owner
db.myCollection.update({“fruit”: “banana”}, {"$set": {“owner”: “xchenhao”}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : "xchenhao" }

已存在情况下则覆盖原有
db.myCollection.update({“fruit”: “banana”}, {"$set": {“owner”: “somebody”}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : "somebody" }

删除字段
db.myCollection.update({“fruit”: “banana”}, {"$unset": {“owner”: 1}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4 }

$push 对数组追加元素

db.myCollection.update({“fruit”: “banana”}, {KaTeX parse error: Expected 'EOF', got '}' at position 28: …r": "xchenhao"}}̲) db.myCollecti…push: {“owner”: “somebody”}})
db.myCollection.update({“fruit”: “banana”}, {$push: {“owner”: “somebody”}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : [ "xchenhao", "somebody", "somebody" ] }

$pop 从数组元素中弹出元素（1 从尾部，-1 从头部）

db.myCollection.update({“fruit”: “banana”}, {$pop: {“owner”: 1}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : [ "xchenhao", "somebody" ] }

$addToSet 添加到集合中（若已存在则不会增加）

KaTeX parse error: Expected '}', got 'EOF' at end of input: …": "banana"}, {addToSet: {“owner”: {$each: [“somebody”, “someone”]}}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : [ "xchenhao", "somebody", "someone" ] }

db.myCollection.update({“fruit”: “banana”}, {$pop: {“owner”: -1}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : [ "somebody", "someone" ] }

$pull 删除数组中完全匹配的元素

db.myCollection.update({“fruit”: “banana”}, {$push: {“owner”: “somebody”}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : [ "somebody", "someone", "somebody" ] }

db.myCollection.update({“fruit”: “banana”}, {$pull: {“owner”: “somebody”}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : [ "someone" ] }

$set 的补充说明：对数组中的某个位置元素进行更新

准备数据
db.myCollection.update({“fruit”: “banana”}, {$set: {“owner”: [“xchenhao”, “somebody”, “someone”]}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : [ "xchenhao", "somebody", "someone" ] }

对数组第一个元素进行更新
db.myCollection.update({“fruit”: “banana”}, {$set: {“owner.0”: “whoami”}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : [ "whoami", "somebody", "someone" ] }

不知道位置则用 $ 代替（查找到的位置）
db.myCollection.update({“owner”: “whoami”}, {KaTeX parse error: Expected '}', got 'EOF' at end of input: set: {"owner.": “It is me”}})
db.myCollection.find()

{ "_id" : ObjectId("5cd69a30b2978f4bd9becafd"), "fruit" : "banana", "count" : 4, "owner" : [ "It is me", "somebody", "someone" ] }

update 第三个参数 upsert（是否在不存在的情况下进行插入）

db.fruit.find()
db.fruit.update({“name”: “apple”}, {$set: {“count”: 100}}, true)

WriteResult({
"nMatched" : 0,
"nUpserted" : 1,
"nModified" : 0,
"_id" : ObjectId("5cd6a66105b099b1e534eaed")
})

db.fruit.find()

{ "_id" : ObjectId("5cd6a66105b099b1e534eaed"), "name" : "apple", "count" : 100 }

db.fruit.update({“name”: “apple”}, {$set: {“count”: 999}}, true)
db.fruit.find()

{ "_id" : ObjectId("5cd6a66105b099b1e534eaed"), "name" : "apple", "count" : 999 }

save() 更新或创建（更新时需要指定 _id）

db.fruit.save({“name”: “banana”, “count”: 10})

WriteResult({ "nInserted" : 1 })

db.fruit.find()

{ "_id" : ObjectId("5cd6a66105b099b1e534eaed"), "name" : "apple", "count" : 999 }{ "_id" : ObjectId("5cd6a6a0b2978f4bd9becafe"), "name" : "banana", "count" : 10 }

db.fruit.save({"_id": ObjectId(“5cd6a6a0b2978f4bd9becafe”), “name”: “banana”, “count”: 800})

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

db.fruit.find()

{ "_id" : ObjectId("5cd6a66105b099b1e534eaed"), "name" : "apple", "count" : 999 }{ "_id" : ObjectId("5cd6a6a0b2978f4bd9becafe"), "name" : "banana", "count" : 800 }

update 第四个参数是否更新多个文档（默认只更新找到的第一个文档）

db.fruit.find()

{ "_id" : ObjectId("5cd6a66105b099b1e534eaed"), "name" : "apple", "count" : 999 }{ "_id" : ObjectId("5cd6a6a0b2978f4bd9becafe"), "name" : "banana", "count" : 800 }

db.fruit.update({}, {$inc: {“count”: -100}}, false, false)

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

db.fruit.find()

{ "_id" : ObjectId("5cd6a66105b099b1e534eaed"), "name" : "apple", "count" : 899 }
{ "_id" : ObjectId("5cd6a6a0b2978f4bd9becafe"), "name" : "banana", "count" : 800 }

db.fruit.update({}, {$inc: {“count”: -100}}, false, true)

WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })

db.fruit.find()

{ "_id" : ObjectId("5cd6a66105b099b1e534eaed"), "name" : "apple", "count" : 799 }
{ "_id" : ObjectId("5cd6a6a0b2978f4bd9becafe"), "name" : "banana", "count" : 700 }

获取上次执行的反馈信息
db.runCommand({getLastError: 1})

{
"connectionId" : 1,
"n" : 0,
"syncMillis" : 0,
"writtenTo" : null,
"err" : null,
"ok" : 1
}

查询 find(query, show_fields)

db.food.find()

{ "_id" : ObjectId("5cd6ec90b2978f4bd9becaff"), "count" : 30, "name" : "薯条" }
{ "_id" : ObjectId("5cd6ecb8b2978f4bd9becb00"), "name" : "炸鸡", "count" : 8 }{ "_id" : ObjectId("5cd6ecc2b2978f4bd9becb01"), "name" : "热狗", "count" : 12 }

第二参数指定是否输出（0 为不输出，除了 _id 外，其它需全为 1 或 0）
参考 https://www.runoob.com/mongodb/mongodb-query.html
db.food.find({}, {“name”: 1, “_id”: 0})

{ "name" : "薯条" }
{ "name" : "炸鸡" }
{ "name" : "热狗" }

查询 count 小于 10
db.food.find({“count”: {$lt: 10}})

{ "_id" : ObjectId("5cd6ecb8b2978f4bd9becb00"), "name" : "炸鸡", "count" : 8 }

查询 count 大于 10 且小于 20
db.food.find({“count”: {$gt: 10, $lt: 20}})

{ "_id" : ObjectId("5cd6ecc2b2978f4bd9becb01"), "name" : "热狗", "count" : 12 }

查询 name 不等于 炸鸡
db.food.find({“name”: {$ne: “炸鸡”}})

{ "_id" : ObjectId("5cd6ec90b2978f4bd9becaff"), "count" : 30, "name" : "薯条" }
{ "_id" : ObjectId("5cd6ecc2b2978f4bd9becb01"), "name" : "热狗", "count" : 12 }

查询 name 属于在热狗、薯条之中的
db.food.find({“name”: {$in: [“热狗”, “薯条”]}})

{ "_id" : ObjectId("5cd6ec90b2978f4bd9becaff"), "count" : 30, "name" : "薯条" }
{ "_id" : ObjectId("5cd6ecc2b2978f4bd9becb01"), "name" : "热狗", "count" : 12 }

查询 name 为薯条或炸鸡
db.food.find({$or: [{“name”: “薯条”}, {“name”: “炸鸡”}]})

{ "_id" : ObjectId("5cd6ec90b2978f4bd9becaff"), "count" : 30, "name" : "薯条" }
{ "_id" : ObjectId("5cd6ecb8b2978f4bd9becb00"), "name" : "炸鸡", "count" : 8 }

db.food2.find()

{ "_id" : ObjectId("5cd6ec90b2978f4bd9becaff"), "count" : 30, "name" : "薯条", "style" : [ "微辣", "香辣" ] }
{ "_id" : ObjectId("5cd6ecb8b2978f4bd9becb00"), "name" : "炸鸡", "count" : 8, "style" : [ "微辣", "香辣" ] }{ "_id" : ObjectId("5cd6ecc2b2978f4bd9becb01"), "name" : "热狗", "count" : 12, "style" : [ "原味" ] }

查询 style 包含香辣及微辣的
db.food2.find({“style”: {$all: [“香辣”, “微辣”]}})

{ "_id" : ObjectId("5cd6ec90b2978f4bd9becaff"), "count" : 30, "name" : "薯条", "style" : [ "微辣", "香辣" ] }
{ "_id" : ObjectId("5cd6ecb8b2978f4bd9becb00"), "name" : "炸鸡", "count" : 8, "style" : [ "微辣", "香辣" ] }

查询 style 只有 1 个
db.food.find({“style”: {$size: 1}})

{ "_id" : ObjectId("5cd6ecc2b2978f4bd9becb01"), "name" : "热狗", "count" : 12, "style" : [ "原味" ] }

按 count 倒序排
db.food.find().sort({“count”: -1})

{ "_id" : ObjectId("5cd6ec90b2978f4bd9becaff"), "count" : 30, "name" : "薯条", "style" : [ "微辣", "香辣" ] }
{ "_id" : ObjectId("5cd6ecc2b2978f4bd9becb01"), "name" : "热狗", "count" : 12, "style" : [ "原味" ] }{ "_id" : ObjectId("5cd6ecb8b2978f4bd9becb00"), "name" : "炸鸡", "count" : 8, "style" : [ "微辣", "香辣" ] }

按 count 倒序排，跳过第 1 个，输出 1 个
db.food.find().sort({“count”: -1}).skip(1).limit(1)

{ "_id" : ObjectId("5cd6ecc2b2978f4bd9becb01"), "name" : "热狗", "count" : 12, "style" : [ "原味" ] }

格式化输出
db.food2.find().pretty()

{
"_id" : ObjectId("5cd6ec90b2978f4bd9becaff"),
"count" : 30,
"name" : "薯条",
"style" : [
"微辣",
"香辣"
]
}
{
"_id" : ObjectId("5cd6ecb8b2978f4bd9becb00"),
"name" : "炸鸡",
"count" : 8,
"style" : [
"微辣",
"香辣"
]
}
{
"_id" : ObjectId("5cd6ecc2b2978f4bd9becb01"),
"name" : "热狗",
"count" : 12,
"style" : [
"原味"
]
}

参考

• https://www.runoob.com/mongodb/mongodb-update.html
• https://github.com/qianjiahao/MongoDB