MongoDB笔记(六) 删除操作(详细)_deletemany 通过objectid批量删除

1.删除全部

> db.collection.remove({})

> db.test.insertMany(
... [
... {item:"铅笔",price:2},
... {item:"钢笔",price:60}
... ]
... )
        "acknowledged" : true,
        "insertedIds" : [
                ObjectId("608bbb44f85311b76bd558fa"),
                ObjectId("608bbb44f85311b76bd558fb")
> db.test.find().pretty()
{ "_id" : ObjectId("608bbb44f85311b76bd558fa"), "item" : "铅笔", "price" : 2 }
        "_id" : ObjectId("608bbb44f85311b76bd558fb"),
        "item" : "钢笔",
        "price" : 60
> db.test.remove({})
WriteResult({ "nRemoved" : 2 })
> db.test.find().pretty()
查询无显示

2.删除符合条件

> db.collection.remove({条件})

> db.test.insertMany( [ {item:"铅笔",price:2}, {item:"钢笔",price:60},{item:"毛笔",price:30}] )
        "acknowledged" : true,
        "insertedIds" : [
                ObjectId("608bbc55f85311b76bd558fc"),
                ObjectId("608bbc55f85311b76bd558fd"),
                ObjectId("608bbc55f85311b76bd558fe")
> db.test.find().pretty()                                                             
{ "_id" : ObjectId("608bbc55f85311b76bd558fc"), "item" : "铅笔", "price" : 2 }
        "_id" : ObjectId("608bbc55f85311b76bd558fd"),
        "item" : "钢笔",
        "price" : 60
        "_id" : ObjectId("608bbc55f85311b76bd558fe"),
        "item" : "毛笔",
        "price" : 30
> db.test.remove({price:{$gt:3}})
WriteResult({ "nRemoved" : 2 })
> db.test.find().pretty()
{ "_id" : ObjectId("608bbc55f85311b76bd558fc"), "item" : "铅笔", "price" : 2 }

3.删除满足条件的单条文档

> db.collection.remove({条件},{justOne:true})

> db.test.insertMany( [ {item:"铅笔",price:2}, {item:"钢笔",price:60},{item:"毛笔",price:30}] )
        "acknowledged" : true,
        "insertedIds" : [
                ObjectId("608bbdc9f85311b76bd558ff"),
                ObjectId("608bbdc9f85311b76bd55900"),
                ObjectId("608bbdc9f85311b76bd55901")
> db.test.find().pretty()                                                                
{ "_id" : ObjectId("608bbdc9f85311b76bd558ff"), "item" : "铅笔", "price" : 2 }
        "_id" : ObjectId("608bbdc9f85311b76bd55900"),
        "item" : "钢笔",
        "price" : 60
        "_id" : ObjectId("608bbdc9f85311b76bd55901"),
        "item" : "毛笔",
        "price" : 30
> db.test.remove({price:{$gt:3}},{justOne:true})
WriteResult({ "nRemoved" : 1 })
> db.test.find().pretty()
{ "_id" : ObjectId("608bbdc9f85311b76bd558ff"), "item" : "铅笔", "price" : 2 }
        "_id" : ObjectId("608bbdc9f85311b76bd55901"),
        "item" : "毛笔",
        "price" : 30
4.delete 
（1）deleteMany() 
> db.books.find().pretty()
        "_id" : ObjectId("608bc487f85311b76bd5590b"),
        "name" : "<a cat story>",
        "price" : 20,
        "color" : "red"
        "_id" : ObjectId("608bc487f85311b76bd5590c"),
        "name" : "<crying birds story>",
        "price" : 20,
        "color" : "green"
        "_id" : ObjectId("608bc487f85311b76bd5590d"),
        "name" : "<big dogs story>",
        "price" : 25,
        "color" : "blue"
> db.books.deleteMany({price:20})
{ "acknowledged" : true, "deletedCount" : 2 }
> db.books.find().pretty()
        "_id" : ObjectId("608bc487f85311b76bd5590d"),
        "name" : "<big dogs story>",
        "price" : 25,
        "color" : "blue"
（2）deleteOne() 
> db.books.find().pretty()
        "_id" : ObjectId("608bcdbff85311b76bd5590f"),
        "name" : "<a cat story>",
        "price" : 20,
        "color" : "red"
        "_id" : ObjectId("608bcdbff85311b76bd55910"),
        "name" : "<crying birds story>",
        "price" : 20,
        "color" : "green"
        "_id" : ObjectId("608bcdbff85311b76bd55911"),
        "name" : "<big dogs story>",
        "price" : 25,
        "color" : "blue"
> db.books.deleteOne({price:20})
{ "acknowledged" : true, "deletedCount" : 1 }
> db.books.find().pretty()
        "_id" : ObjectId("608bcdbff85311b76bd55910"),
        "name" : "<crying birds story>",
        "price" : 20,
        "color" : "green"
        "_id" : ObjectId("608bcdbff85311b76bd55911"),
        "name" : "<big dogs story>",
        "price" : 25,
        "color" : "blue"
下一篇：MongoDB笔记(七) 索引(详细)
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删除多行数据db.collections.deleteMany()
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小技巧：手动创建一个后缀为bat的文件，文件名任意，内容为： mongod –dbpath=D:\mongo_data，双击此文件就可以启动MongoDB服务，不用每次都到命令行执行启动命令 
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