MongoDB：删除操作

一. 根据查询条件删除文档

1. 查询 id=1 的所有文档

test:PRIMARY> db.test_1.find({id:1})
{ "_id" : ObjectId("58a11caca14d421caf8c45db"), "id" : 1, "name" : "name_1" }
{ "_id" : ObjectId("58a11cada14d421caf8c45dc"), "id" : 1, "name" : "swrd" }

2. 删除 id=1 的所有文档，查看里面已无id等于1的数据

test:PRIMARY> db.test_1.remove({id:1})
WriteResult({ "nRemoved" : 2 })
test:PRIMARY> db.test_1.find({id:1})
test:PRIMARY>

二. 删除一个集合中的所有文档

1. 查询 test_1 集合的所有文档

test:PRIMARY> db.test_1.find()
{ "_id" : ObjectId("58a11dd8a14d421caf8c45dd"), "id" : 2, "name" : "name_2" }
{ "_id" : ObjectId("58a11dd8a14d421caf8c45de"), "id" : 3, "name" : "name_3" }
{ "_id" : ObjectId("58a11dd8a14d421caf8c45df"), "id" : 4, "name" : "name_4" }
{ "_id" : ObjectId("58a11dd8a14d421caf8c45e0"), "id" : 5, "name" : "name_5" }
{ "_id" : ObjectId("58a11dd8a14d421caf8c45e1"), "id" : 6, "name" : "name_6" }
{ "_id" : ObjectId("58a11dd8a14d421caf8c45e2"), "id" : 7, "name" : "name_7" }

2. 删除 test_1 集合的所有文档

test:PRIMARY> db.test_1.remove({})
WriteResult({ "nRemoved" : 6 })
test:PRIMARY> db.test_1.find()

三、删除集合

test:PRIMARY> show tables;
test_1
test_2
test_3
test_4
test:PRIMARY> db.test_4.drop()
true
test:PRIMARY> show tables;
test_1
test_2
test_3

四、删除数据库

test:PRIMARY> show dbs
local          0.000GB
log            0.089GB
student        0.000GB
swrd           0.000GB
test           0.000GB
test:PRIMARY> db
test
test:PRIMARY> db.test.getDB()
test
test:PRIMARY> show tables;
test_1
test:PRIMARY> db.dropDatabase()
{ "dropped" : "test", "ok" : 1 }
test:PRIMARY> show dbs
local          0.000GB
log            0.089GB
student        0.000GB
swrd           0.000GB

在执行删除整个数据库前，要谨慎，执行db命令查看当前的使用的数据库，可确保误删除，造成数据的丢失.