MongoDB快速入门笔记(六)之MongoDB的文档修改操作

2020-10-29 18:49:35

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MongoDB

MongoDB 是一个开源的文档数据库，并领先的 NoSQL 数据库。 MongoDB 是由 c++语言编写。

文档

文档是一组键 - 值对。文件动态模式。动态模式是指，在相同集合中的文档不需要具有相同的字段或结构组的公共字段的集合的文档，可以容纳不同类型的数据。

db.集合名称.update({query},{update},upsert, multi})
query:过滤条件
update:修改内容
upsert：如果不存在查询条件查出的记录，是否插入一条数据，默认是false
multi：是否只修改查询条件查出的第一条记录，默认是false

> db.student.update({_id:1}, {name:"zhang"})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhang" }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }

把整条数据都修改了，如果修改内容中没有设置age字段，则以前的age也取消了，数据全部修改

局部修改

$set:如果存在键则修改，如果不存在键则添加

> db.student.update({_id: 1},{$set:{name:"zhangsan", age: 26}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }

id重复时无法修改

> db.student.update({_id:1},{_id:0, name:"zhangsanzhangsan"})WriteResult({"nMatched" : 0,"nUpserted" : 0,"nModified" : 0,"writeError" : {"code" : 16837,"errmsg" : "The _id field cannot be changed from {_id: 1.0} to {_id: 0.0}."}})> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }

第三个参数默认为false，如果查不到数据false时不执行任何操作，true时往数据库里新插入一条数据

> db.student.update({_id:7},{_id:7, name: "songjiu", age:32})WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })> db.student.update({_id:7},{_id:7, name: "songjiu"}, true)WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : 7 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "age" : 32 }

第四个参数默认为false，false时表示只修改查询到的第一条数据，true时表示修改查询到的所有数据

> db.student.update({age:32}, {$set:{age:33}}, false, false)WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 33 }{ "_id" : 7, "name" : "songjiu", "age" : 32 }> db.student.update({age:33}, {$set:{age:32}}, false, true)WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 32 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "age" : 32 }> db.student.update({age:32}, {$set:{age:33}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "age" : 32 }

$inc:在原来的基础上加多少

> db.student.update({_id:7}, {$inc:{age:-1}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "age" : 31 }

$unset:去掉某个键

> db.student.update({_id:7},{$unset:{age:1}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu" }

针对数组类型的操作

$push:当数据中不存在键时，创建数组类型的键并插入该值;如果存在该键，并且该键是数组类型时，则在此数组类型的数据上追加;如果存在该键，并且该键不是数组类型时，会报错。
$pushAll:批量往数组中追加
$addToSet:数组中有该值时不追加，没有该值时追加

> db.student.update({_id: 7},{$push:{skill:"java"}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "skill" : [ "java" ] }> db.student.update({_id: 7},{$push:{skill:"mongodb"}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "skill" : [ "java", "mongodb" ] }> db.student.update({_id: 7},{$push:{name:"111"}})WriteResult({"nMatched" : 0,"nUpserted" : 0,"nModified" : 0,"writeError" : {"code" : 16837,"errmsg" : "The field 'name' must be an array but is of type String in document {_id: 7.0}"}})> db.student.update({_id: 7},{$pushAll:{skill:["js","C++","java"]}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "skill" : [ "java", "mongodb", "js", "C++", "java" ] }> db.student.update({_id:7},{$addToSet:{skill:"mongodb"}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "skill" : [ "java", "mongodb", "js", "C++", "java" ] }

$pop:删除数组的第一个或最后一个元素，值为-1时是删除第一个元素，值为1时是删除最后一个元素。

$pull:删除数组中的某一个指定的数值

$pullAll:删除数组中多个指定的数值

> db.student.update({_id:7},{$pop:{skill:1}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "skill" : [ "java", "mongodb", "js", "C++" ] }> db.student.update({_id:7},{$pop:{skill:-1}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "skill" : [ "mongodb", "js", "C++" ] }> db.student.update({_id:7},{$pull:{skill:"js"}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "skill" : [ "mongodb", "C++" ] }> db.student.update({_id:7},{$pullAll:{skill:["js"]}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "skill" : [ "mongodb", "C++" ] }> db.student.update({_id:7},{$pullAll:{skill:["mongodb","C++"]}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.student.find(){ "_id" : 1, "name" : "zhangsan", "age" : 26 }{ "_id" : 2, "name" : "lisi", "age" : 27 }{ "_id" : 3, "name" : "wangwu", "age" : 30 }{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }{ "_id" : 5, "name" : "qianliu", "age" : 33 }{ "_id" : 6, "name" : "sunba", "age" : 32 }{ "_id" : 7, "name" : "songjiu", "skill" : [ ] }

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