标签：err for log value 类型 rem not upd 添加
可以使用修改器啦修改文档，比如增加、删除文档的键值。使用修改器首先要定位到某个文档， 然后再增加相应的修改选项,需要使用update语句
1.$inc修改器修改文档
> db.users.findOne({‘name‘:‘cd‘}); { "_id" : ObjectId("584eafa97629396db95535da"), "name" : "cd", "sex" : "M", "information" : { "age" : 23, "address" : "Shanghai" } } > db.users.update({"name": "cd"}, ... {"$inc":{"qq": 123456789}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.users.findOne({‘name‘:‘cd‘}); { "_id" : ObjectId("584eafa97629396db95535da"), "name" : "cd", "sex" : "M", "information" : { "age" : 23, "address" : "Shanghai" }, "qq" : 123456789 } >
命令解释：
db.users.findOne() -->查询某个文档，可以添加具体的参数，只返回一个文档，如上例子查询文档键name的值为cd的该文档
db.users.update() -->更新某个文档，一般带有两个参数，一个参数定位到更新那个文档，另一个参数设置修改内容
{"$inc":{"key" : "value"}}-->修改键key对应的值，若key不存在，则创建key
流程：
1.首先查询name为cd的文档，看文档里面的具体键值
2.使用修改器$inc和更新语句更新集合中的文档
3.再次查询name为cd的文档，和步骤1的查询结果对比，看更新文档是否成功
2.$set修改器修改文档
> db.users.findOne({"name":"scd"}); { "_id" : ObjectId("58549695a14618fbeef3bf0f"), "name" : "scd", "sex" : "M", "address" : "上海" } > db.users.update( {"name":"scd"}, ... {"$set":{"lang": ["中文", "english"]}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.users.findOne({"name":"scd"}); { "_id" : ObjectId("58549695a14618fbeef3bf0f"), "name" : "scd", "sex" : "M", "address" : "上海", "lang" : [ "中文", "english" ] } >
3.$uset修改器，删除文档中的某个键
> db.users.findOne({"name":"scd"}); { "_id" : ObjectId("58549885a14618fbeef3bf11"), "name" : "scd", "sex" : "M", "address" : "上海", "lang" : [ "中文", "english" ] } > db.users.update({"name":"scd"}, ... {"$unset":{"sex":"M"}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.users.findOne({"name":"scd"}); { "_id" : ObjectId("58549885a14618fbeef3bf11"), "name" : "scd", "address" : "上海", "lang" : [ "中文", "english" ] } >
操作结果：删除键name值为scd文档的键sex
4.$set和$inc修改器的区别
$inc只能由于修改整型、长整型或双精度浮点型的值
> db.users.findOne({"name":"scd"}); { "_id" : ObjectId("58549885a14618fbeef3bf11"), "name" : "scd", "address" : "上海", "lang" : [ "中文", "english" ] } > db.users.update({"name":"scd"}, ... {"$inc":{"address": "北京"}}); WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0, "writeError" : { "code" : 14, "errmsg" : "Cannot increment with non-numeric argument: {address: \"鍖椾含\"}" } })
使用$inc修改键对应的数值为字符串会报错 "writeError"
而使用$set可以修改键对应的值为字符类型的数值
> db.users.findOne({"name":"scd"}); { "_id" : ObjectId("58549885a14618fbeef3bf11"), "name" : "scd", "address" : "上海", "lang" : [ "中文", "english" ] }
> db.users.update({"name":"scd"}, ... {"$set":{"address":"北京"}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.users.findOne("name":"scd"); 2016-12-17T09:55:20.213+0800 E QUERY [thread1] SyntaxError: missing ) after argument list @(shell):1:23 > db.users.findOne({"name":"scd"}); { "_id" : ObjectId("58549885a14618fbeef3bf11"), "name" : "scd", "address" : "北京", "lang" : [ "中文", "english" ] } >
$set修改器可以修改许多类型的数值，如字符串、数组等等
标签：err for log value 类型 rem not upd 添加
原文地址：http://www.cnblogs.com/shootercheng/p/6189148.html
