文档插入方式一: > db.mongo.insert({name:"jack",age: 30}); WriteResult({ "nInserted" : 1 }) > db.mongo.find(); { "_id" : ObjectId("54ded72e0dc51419494b4565"), "name" : "jack", "age" : 30 } 文档插入方式二: > j = { name : "mongo" }; { "name" : "mongo" } > t = { x : 3 }; { "x" : 3 } > i = {name : "jack"}; { "name" : "jack" } > db.things.save(j); WriteResult({ "nInserted" : 1 }) > db.things.save(t); WriteResult({ "nInserted" : 1 }) > db.things.save(i); WriteResult({ "nInserted" : 1 }) > db.things.find(); { "_id" : ObjectId("54ded4960dc51419494b4562"), "name" : "mongo" } { "_id" : ObjectId("54ded4ad0dc51419494b4563"), "x" : 3 } { "_id" : ObjectId("54ded6690dc51419494b4564"), "name" : "jack" } 我们已经把数据插入到表mongo和表things里面了。 当我们find()查询的时候,会发现文档里会自动生生一个字段:_id, 如"_id" : ObjectId("54ded4960dc51419494b4562") 在mongo中,集合都必须有??_id字段,默认是ObjectId,并且必须唯一,如果插入重复的值的话,就会抛出异常。当然也可以不为ObjectId 插入一个_id为1的数据: > db.mongo.insert({_id:1,name:"wang",age: 20}); WriteResult({ "nInserted" : 1 }) 再次插入一个_id为1的数据就会报错: > db.mongo.insert({_id:1,name:"fang",age: 22}); WriteResult({ "nInserted" : 0, "writeError" : { "code" : 11000, "errmsg" : "insertDocument :: caused by :: 11000 E11000 duplicate key error index: test.mongo.$_id_ dup key: { : 1.0 }" } }) 我们查询mongo表中的内容,_id字段可以不为ObjectId: > db.mongo.find(); { "_id" : ObjectId("54ded72e0dc51419494b4565"), "name" : "jack", "age" : 30 } { "_id" : 1, "name" : "wang", "age" : 20 } > 文档的删除: > db.mongo.find(); { "_id" : ObjectId("54ded72e0dc51419494b4565"), "name" : "jack", "age" : 30 } { "_id" : 1, "name" : "wang", "age" : 20 } 删除name值为wang的文档: > db.mongo.remove({"name":"wang"}) WriteResult({ "nRemoved" : 1 }) > db.mongo.find(); { "_id" : ObjectId("54ded72e0dc51419494b4565"), "name" : "jack", "age" : 30 } > 删除整个文档,但不是删除collection本身和索引 > db.mongo.insert({_id:1,name:"fang",age: 22}); WriteResult({ "nInserted" : 1 }) > db.mongo.find(); { "_id" : ObjectId("54ded72e0dc51419494b4565"), "name" : "jack", "age" : 30 } { "_id" : 1, "name" : "fang", "age" : 22 } > db.mongo.remove({}) WriteResult({ "nRemoved" : 2 }) > show collections mongo system.indexes things > db.mongo.find(); > |
|
来自: 昵称21365845 > 《MongoDB》