【MongoDB学习笔记13】MongoDB的更新（update）操作进阶

一、批量更新

默认只对符合条件的一条文档更新

> db.post.find()   { "_id" : ObjectId("54a530c3ff0df3732bac1681"), "id" : 2, "name" : "joe", "age" : 49 }   { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 21, "comments" : [ "test2", "test9", "test5" ] }> db.post.update({"name":"joe"}, {$set:{"age":70}})   WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })    > db.post.find()    { "_id" : ObjectId("54a530c3ff0df3732bac1681"), "id" : 2, "name" : "joe", "age" : 70 }  { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 21, "comments" : [ "test2", "test9", "test5" ] }    >

利用update的第四个参数进行批量更新：

> db.post.update({"name":"joe"}, {$set:{"age":30}},false,true)   WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })> db.post.find()    { "_id" : ObjectId("54a530c3ff0df3732bac1681"), "id" : 2, "name" : "joe", "age" : 30 }   { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 30, "comments" : [ "test2", "test9", "test5" ] }    >

附注：update方法参考

update( criteria, objNew, upsert, multi )
criteria : update的查询条件，类似sql update查询内where后面的
objNew : update的对象和一些更新的操作符（如$,$inc...）等，也可以理解为sql update查询内set后面的
upsert : 这个参数的意思是，无论false还是true，没有匹配的键则新增加一个；

multi : mongodb默认是false,只更新找到的第一条记录，如果这个参数为true,就把按条件查出来多条记录全部更新。

二、更新文档键值，无键值的则新增键值；

> db.post.update({"name":"joe"}, {$set:{"sex":1}},false,true)   WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })    > db.post.find()    { "_id" : ObjectId("54a530c3ff0df3732bac1681"), "id" : 2, "name" : "joe", "age" : 30, "sex" : 1 }    { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 30, "comments" : [ "test2", "test9", "test5" ], "sex" : 1 }    > db.post.update({"name":"joe"}, {$set:{"school":"marry"}},true,true)    WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })    > db.post.find()    { "_id" : ObjectId("54a530c3ff0df3732bac1681"), "id" : 2, "name" : "joe", "age" : 30, "sex" : 1, "school" : "marry" }    { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 30, "comments" : [ "test2", "test9", "test5" ], "sex" : 1, "school" : "marry" }    >