Mongodb删除操作

不管是数据库还是操作系统的文件，进行删除操作需要谨慎，确认确认再确认。 MongoDB提供以下方法来删除集合中的文档delete、drop、remove。drop操作会删除集合及索引文件。

1、remove 删除单个文档或匹配指定筛选器的所有文档。

rs02:PRIMARY> db.mycoll.find()
{ "_id" : 1, "category" : "café", "status" : "A" }
{ "_id" : 2, "category" : "cafe", "status" : "a" }
{ "_id" : 3, "category" : "cafE", "status" : "a" }
rs02:PRIMARY> db.mycoll.remove({"status" : "A"})  //删除集合中"status" 值等于"A"的文档
WriteResult({ "nRemoved" : 1 })
rs02:PRIMARY> db.mycoll.find()
{ "_id" : 2, "category" : "cafe", "status" : "a" }
{ "_id" : 3, "category" : "cafE", "status" : "a" }
rs02:PRIMARY> db.mycoll.remove({})           //删除集合中的所有文档
WriteResult({ "nRemoved" : 2 })
rs02:PRIMARY> db.mycoll.find()
rs02:PRIMARY> db.mycoll.getIndexes()    //索引还在
[
	{
		"v" : 2,
		"key" : {
			"_id" : 1
		},
		"name" : "_id_",
		"ns" : "test_jia.mycoll"
	}
]
rs02:PRIMARY>

2、使用命令deleteOne和deleteMany删除文档

rs02:PRIMARY> db.inventory.find()
{ "_id" : ObjectId("6386a8ab9011e974ab4118f2"), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "status" : "A" }
{ "_id" : ObjectId("6386a8ab9011e974ab4118f3"), "item" : "notebook", "qty" : 50, "size" : { "h" : 8.5, "w" : 11, "uom" : "in" }, "status" : "P" }
{ "_id" : ObjectId("6386a8ab9011e974ab4118f4"), "item" : "paper", "qty" : 100, "size" : { "h" : 8.5, "w" : 11, "uom" : "in" }, "status" : "D" }
{ "_id" : ObjectId("6386a8ab9011e974ab4118f5"), "item" : "planner", "qty" : 75, "size" : { "h" : 22.85, "w" : 30, "uom" : "cm" }, "status" : "D" }
{ "_id" : ObjectId("6386a8ab9011e974ab4118f6"), "item" : "postcard", "qty" : 45, "size" : { "h" : 10, "w" : 15.25, "uom" : "cm" }, "status" : "A" }

rs02:PRIMARY> db.inventory.getIndexes()  //查看索引
[
	{
		"v" : 2,
		"key" : {
			"_id" : 1
		},
		"name" : "_id_",
		"ns" : "test_jia.inventory"
	}
]

2.1、deleteOne删除文档

rs02:PRIMARY> db.inventory.deleteOne( { status: "D" } )  //deleteOne删除文档删除条件是status值为 "D"
{ "acknowledged" : true, "deletedCount" : 1 }
rs02:PRIMARY> db.inventory.find()     //查看数据
{ "_id" : ObjectId("6386a8ab9011e974ab4118f2"), "item" : "journal", "qty" : 25, "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "status" : "A" }
{ "_id" : ObjectId("6386a8ab9011e974ab4118f3"), "item" : "notebook", "qty" : 50, "size" : { "h" : 8.5, "w" : 11, "uom" : "in" }, "status" : "P" }
{ "_id" : ObjectId("6386a8ab9011e974ab4118f5"), "item" : "planner", "qty" : 75, "size" : { "h" : 22.85, "w" : 30, "uom" : "cm" }, "status" : "D" }
{ "_id" : ObjectId("6386a8ab9011e974ab4118f6"), "item" : "postcard", "qty" : 45, "size" : { "h" : 10, "w" : 15.25, "uom" : "cm" }, "status" : "A" }

2.2、deleteMany删除文档

rs02:PRIMARY> db.inventory.deleteMany({ status : "A" })     //deleteMany删除符合status值为 "A"
{ "acknowledged" : true, "deletedCount" : 2 }

rs02:PRIMARY> db.inventory.find()                          //查看数据
{ "_id" : ObjectId("6386a8ab9011e974ab4118f3"), "item" : "notebook", "qty" : 50, "size" : { "h" : 8.5, "w" : 11, "uom" : "in" }, "status" : "P" }
{ "_id" : ObjectId("6386a8ab9011e974ab4118f5"), "item" : "planner", "qty" : 75, "size" : { "h" : 22.85, "w" : 30, "uom" : "cm" }, "status" : "D" }  

rs02:PRIMARY> db.inventory.deleteMany({})                 //删除集合中所有文档
{ "acknowledged" : true, "deletedCount" : 2 }
rs02:PRIMARY> db.inventory.find()
rs02:PRIMARY> db.inventory.getIndexes()                  //索引还在
[
	{
		"v" : 2,
		"key" : {
			"_id" : 1
		},
		"name" : "_id_",
		"ns" : "test_jia.inventory"
	}

3、drop删除集合

rs02:PRIMARY> db.inventory.drop()    //删除集合包括索引文件
true
rs02:PRIMARY> db.inventory.find()
rs02:PRIMARY>

3、drop数据库

db.dropDatabase() 删除当前数据库，删除相关的数据文件,

rs02:PRIMARY> use user_info
switched to db user_info
rs02:PRIMARY> show tables;
ip
test1
rs02:PRIMARY> db.dropDatabase()
{
	"dropped" : "user_info",
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1669790100, 3),
		"signature" : {
			"hash" : BinData(0,"A8ZFmKSlf9XsyZXbwpZ2UX6Q6vo="),
			"keyId" : NumberLong("7152775128156209153")
		}
	},
	"operationTime" : Timestamp(1669790100, 3)
}
rs02:PRIMARY>