MongoDB快速入门笔记(六)之MongoDB的文档修改操作-木庄网络博客

本文整理自网络，侵删。

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

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