mongodb修改器：

mongodb修改器：    $inc        用来增加或减少已有的键的键值(（只能为满足要求的数字）)，或者在键不存在的时候创建一个键。{"$inc":{"k1":±数字}}    $set        1.修改器用来指定一个键值。如果这个键不存在，则创建他，2.修改内嵌文档.例：{"$set":{"k1.k11":"v11"}}    $unset      用于将键删除.{"$unset":{"k1":1}}    $push       数组修改器，如果指定的值已经存在，"$push"会想已有的数组末尾加入一个元素，要是没有就会创建一个新的数组。例：{"$push":{"k1":{"k11":"v11","k12":"v12"}}    $ne         如果一个值不在数组里面就把他加进去，如果在不添加。例：update({"k1":"v1","k2":{$ne:"v2n"}},{$push:{"k2":"v2n"}})    $addToSet   如果一个值不在数组里面就把他加进去，如果在不添加。可避免重复。例：update({"k1":v1},{$addToSet:{"k2":"v2n"}})    $each       和$addToSet修改结合起来用，可以一次添加多个不同的值。例：{"k1":v1},{$addToSet:{"k2":{$each:["v21","v22","v21"]}}}    $pop        从数组中删除元素，他可以从数组中的任何一端删除元素。例：{$pop:{key:1}} 从数组末尾删除一个元素.{$pop:{key:-1}} 从数组头部删除一个元素.    $pull       基于特定条件来删除元素。例：{$pull:{"k2":"v2n"}}    $           数组的定位修改器.                update({"k1":"v1"},{$set:{"k2.number.k2n":"newDate"}})//k2为数组，number为数组第几个,0为第一个，                update({"k2.k2n":"k2n"},{$set:{"k2.$.k2m":"v2m"}})

详细解读：

1.$set修改器--------------------------------------------------------------------------------$set修改器用来指定一个键值，如果这个键不存在,则创建他。修改内嵌文档,对于内嵌文档在使用$set更新时，使用"."连接的方式例一：> db.users.findOne(){        "_id" : ObjectId("56fe7df8b322e3ff1dabf834"),        "name" : "joe",        "favorite book" : "war and pace"}> db.users.update({"name":"joe"},{"$set":{"favorite book":["cat's cardle","foundation trilogy","ender's game"]}})//添加键值对WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.users.findOne(){        "_id" : ObjectId("56fe7df8b322e3ff1dabf834"),        "name" : "joe",        "favorite book" : [                "cat's cardle",                "foundation trilogy",                "ender's game"        ]}例二：> db.blog.findOne(){        "_id" : ObjectId("57709da84f533aa7535d46d3"),        "title" : "a blog post",        "author" : {                "name" : "joe",                "email" : "[e-mail]"        }}> db.blog.update({"author.name":"joe"},{"$set":{"author.name":"joe schmoe"}})//修改键值WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.blog.findOne(){        "_id" : ObjectId("57709da84f533aa7535d46d3"),        "title" : "a blog post",        "author" : {                "name" : "joe schmoe",                "email" : "[e-mail]"        }}2.$inc修改器--------------------------------------------------------------------------------$inc其用来增加或减少已有的键的键值(键值必须是数字)，或者在键不存在的时候创建一个键。> db.games.findOne(){        "_id" : ObjectId("5770a1394f533aa7535d46d4"),        "game" : "pinball",        "user" : "joe"}> db.games.update({"game":"pinball","user":"joe"},{"$inc":{"score":50}})//键值不存在时WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.games.findOne(){        "_id" : ObjectId("5770a1394f533aa7535d46d4"),        "game" : "pinball",        "user" : "joe",        "score" : 50}> db.games.update({"game":"pinball","user":"joe"},{"$inc":{"score":50}})//增加WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.games.findOne(){        "_id" : ObjectId("5770a1394f533aa7535d46d4"),        "game" : "pinball",        "user" : "joe",        "score" : 100}> db.games.update({"game":"pinball","user":"joe"},{"$inc":{"score":-20}})//减少WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.games.findOne(){        "_id" : ObjectId("5770a1394f533aa7535d46d4"),        "game" : "pinball",        "user" : "joe",        "score" : 80}3.$unset修改器--------------------------------------------------------------------------------$unset修改器将键删除> db.users.findOne(){        "_id" : ObjectId("56fe7df8b322e3ff1dabf834"),        "name" : "joe",        "age" : 30,        "favorite book" : [                "cat's cardle",                "foundation trilogy",                "ender's game"        ]}> db.users.update({"name":"joe"},{"$unset":{"favorite book":1}})//删除键为：favorite book的键值对WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.users.findOne(){        "_id" : ObjectId("56fe7df8b322e3ff1dabf834"),        "name" : "joe",        "age" : 30,}数组修改器：1.$push修改器--------------------------------------------------------------------------------$push修改器如果指定的值已经存在，"$push"会想已有的数组末尾加入一个元素，要是没有就会创建一个新的数组。> db.blog.findOne(){ "_id" : ObjectId("57709da84f533aa7535d46d3"), "title" : "a blog post"}> db.blog.update({"title":"a blog post"},{"$push":{"comments":{"name":"joe","email":"[e-mail]","content":"nice post"}}})//键值对不存在WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.blog.findOne(){        "_id" : ObjectId("57709da84f533aa7535d46d3"),        "title" : "a blog post",        "comments" : [                {                        "name" : "joe",                        "email" : "[e-mail]",                        "content" : "nice post"                }        ]}> db.blog.update({"title":"a blog post"},{"$push":{"comments":{"name":"bob","email":"[e-mail]","content":"good post"}}})//键值存在,在已有数组下添加元素WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.blog.findOne(){        "_id" : ObjectId("57709da84f533aa7535d46d3"),        "title" : "a blog post",        "comments" : [                {                        "name" : "joe",                        "email" : "[e-mail]",                        "content" : "nice post"                },                {                        "name" : "bob",                        "email" : "[e-mail]",                        "content" : "good post"                }        ]}2.数组修改器 $ne--------------------------------------------------------------------------------在查询文档中，如果一个值不在数组里面就把他加进去，如果在不添加。> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}> db.users.update({"name":"joe","emails":{$ne:"[e-mail]"}},{$push:{"emails":"[e-mail]"}})//值在数组里面,没有改变WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })                                    --nMatched为0表示没有修改> db.users.update({"name":"joe","emails":{$ne:"[e-mail]"}},{$push:{"emails":"[e-mail]"}})//值不在数组里面,添加WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}3.数组修改器 $addToSet--------------------------------------------------------------------------------实现的功能与$ne修改器相同，且更为方便。使用$addToSet修改器可以避免重复。> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}> db.users.update({"_id":ObjectId("5770ca42e90c1adc80040a08")},{$addToSet:{"emails":"[e-mail]"}})--原文档里已有"[e-mail]",修改完也没有产生重复值WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}> db.users.update({"_id":ObjectId("5770ca42e90c1adc80040a08")},{$addToSet:{"emails":"[e-mail]"}})--不存在添加成功WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}4.数组修改器 $each--------------------------------------------------------------------------------$each数组修改器要和$addToSet修改结合起来用，可以一次添加多个不同的值。例如上面的例子中，我们一次添加多个email值。> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}> db.users.update({"_id":ObjectId("5770ca42e90c1adc80040a08")},{$addToSet:{"emails":{$each:["[e-mail]","[e-mail]","[e-mail]"]}}})--为数组添加多个键值WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}5.数组修改器 $pop--------------------------------------------------------------------------------$pop修改器从数组中删除元素，可以从数组中的任何一端删除元素，{$pop:{key:1}} 从数组末尾删除一个元素{$pop:{key:-1}} 从数组头部删除一个元素> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}> db.users.update({"name":"joe"},{$pop:{"emails":1}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}> db.users.update({"name":"joe"},{$pop:{"emails":-1}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}6.数组修改器 $pull--------------------------------------------------------------------------------用来删除数组中的元素，pull可以按特定条件来删除元素，会将所有匹配到的数据全部删掉。但是删除条件只能有一个> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}> db.users.update({"name":"joe"},{$pull:{"emails":["[e-mail]","[e-mail]"]}})   WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })--好像不能一次删除多个，没有起作用> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}> db.users.update({"name":"joe"},{$pull:{"emails":"[e-mail]"}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.users.update({"name":"joe"},{$pull:{"emails":"[e-mail]"}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.users.findOne(){        "_id" : ObjectId("5770ca42e90c1adc80040a08"),        "name" : "joe",        "emails" : [                "[e-mail]",                "[e-mail]",                "[e-mail]"        ]}7.数组的定位修改器 $--------------------------------------------------------------------------------若是数组有多个值，而我们只想对其中一部分进行操作，mongodb提供了定位操作符"$",用来定位查询文档已经匹配的元素，并进行更新,定位符只更新第一个匹配的元素。方法一：使用数组下标> db.blog.findOne(){        "_id" : ObjectId("57709da84f533aa7535d46d3"),        "title" : "a blog post",        "comments" : [                {                        "name" : "joe",                        "email" : "[e-mail]",                        "content" : "nice post"                },                {                        "name" : "bob",                        "email" : "[e-mail]",                        "content" : "good post"                }        ]}> db.blog.update({"title":"a blog post"},{$set:{"comments.1.name":"livan"}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.blog.findOne(){        "_id" : ObjectId("57709da84f533aa7535d46d3"),        "title" : "a blog post",        "comments" : [                {                        "name" : "joe",                        "email" : "[e-mail]",                        "content" : "nice post"                },                {                        "name" : "livan",                        "email" : "[e-mail]",                        "content" : "good post"                }        ]}--方法二：使用$> db.blog.findOne(){        "_id" : ObjectId("57709da84f533aa7535d46d3"),        "title" : "a blog post",        "comments" : [                {                        "name" : "joe",                        "email" : "[e-mail]",                        "content" : "nice post"                },                {                        "name" : "livan",                        "email" : "[e-mail]",                        "content" : "good post"                }        ]}> db.blog.update({"comments.name":"livan"},{$set:{"comments.$.email":"[e-mail]"}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.blog.update({"comments.name":"livan"},{$set:{"comments.$.name":"bob"}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.blog.findOne(){        "_id" : ObjectId("57709da84f533aa7535d46d3"),        "title" : "a blog post",        "comments" : [                {                        "name" : "joe",                        "email" : "[e-mail]",                        "content" : "nice post"                },                {                        "name" : "bob",                        "email" : "[e-mail]",                        "content" : "good post"                }        ]}

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