mongodb update 字符 操作（补充）

数组相关更新操作

 3. $push

用来增加数组。若没有改列，则会自动增加。

> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "name" : "xtt" }

> db.tianyc03.update({'name':'xtt'},{$push:{companies:'neu'}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "neu" ], "name" : "xtt" }

> db.tianyc03.update({'name':'xtt'},{$push:{companies:'alibaba'}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "neu", "alibaba" ], "name" : "xtt" }

4. $addToSet

#push操作不会检查数组中元素是否重复，如果需要将不重复的数据加入数组，需要使用$addToSet

> db.tianyc03.update({'name':'xtt'},{$addToSet:{companies:'alibaba'}})

> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "neu", "alibaba", "alibaba" ], "name" : "xtt" }
> db.tianyc03.update({'name':'xtt'},{$addToSet:{companies:'congxing'}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "neu", "alibaba", "alibaba", "congxing" ], "name" : "xtt" }
> db.tianyc03.update({'name':'xtt'},{$addToSet:{companies:'congxing'}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "neu", "alibaba", "alibaba", "congxing" ], "name" : "xtt" }
>

5. $pop

通过$pop可以从数组中移除数据。此时数据被看成是一个队列。使用{$pop:{key:1}}将从队列末尾移除元素，使用{$pop:{key:-1}}将从队列开头移除元素。

> db.tianyc03.update({'name':'xtt'},{$addToSet:{companies:['c1','c2']}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "neu", "alibaba", "alibaba", "congxing", [ "c1", "c2" ] ], "name" : "xtt" }

> db.tianyc03.update({'name':'xtt'},{$pop:{companies:1}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "neu", "alibaba", "alibaba", "congxing" ], "name" : "xtt" }
>
> db.tianyc03.update({'name':'xtt'},{$pop:{companies:-1}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "alibaba", "alibaba", "congxing" ], "name" : "xtt" }
>

6. $pull

除了 $pop，也可以使用 $pull 来删除数组中的元素，此时可以根据元素值进行匹配，将匹配上的元素全部删除。

> db.tianyc03.update({'name':'xtt'},{$addToSet:{companies:'teletek'}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "alibaba", "alibaba", "congxing", "teletek" ], "name" : "xtt" }
> db.tianyc03.update({},{$pull:{companies:'congxing'}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "alibaba", "alibaba", "teletek" ], "name" : "xtt" }

> db.tianyc03.update({},{$pull:{companies:'alibaba'}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "companies" : [ "teletek" ], "name" : "xtt" }
>

批量更新

3. 批量更新

默认情况下，update只更新匹配到的第一行记录。将update的第四个参数设置为true，则批量更新搜索到的所有记录。

> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "count" : 11 }
{ "_id" : ObjectId("510f1a9f6010b3da16ea6618"), "count" : 26 }
{ "_id" : ObjectId("510f1aa76010b3da16ea6619"), "count" : 23 }
{ "_id" : ObjectId("510f1b718474cd8af024e2d0"), "count" : 244 }
{ "_id" : ObjectId("510f1c8f8474cd8af024e2d1"), "count" : 24 }
#将所有count值增加10，但却只增加了第一行。

> db.tianyc03.update({},{$inc:{count:10}}) 
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "count" : 21 }
{ "_id" : ObjectId("510f1a9f6010b3da16ea6618"), "count" : 26 }
{ "_id" : ObjectId("510f1aa76010b3da16ea6619"), "count" : 23 }
{ "_id" : ObjectId("510f1b718474cd8af024e2d0"), "count" : 244 }
{ "_id" : ObjectId("510f1c8f8474cd8af024e2d1"), "count" : 24 }

#再增加一次，还是只增加了第一行。

> db.tianyc03.update({},{$inc:{count:10}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "count" : 31 }
{ "_id" : ObjectId("510f1a9f6010b3da16ea6618"), "count" : 26 }
{ "_id" : ObjectId("510f1aa76010b3da16ea6619"), "count" : 23 }
{ "_id" : ObjectId("510f1b718474cd8af024e2d0"), "count" : 244 }
{ "_id" : ObjectId("510f1c8f8474cd8af024e2d1"), "count" : 24 }

#使用批量更新，达到目的。

> db.tianyc03.update({},{$inc:{count:10}},false,true)
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "count" : 41 }
{ "_id" : ObjectId("510f1a9f6010b3da16ea6618"), "count" : 36 }
{ "_id" : ObjectId("510f1aa76010b3da16ea6619"), "count" : 33 }
{ "_id" : ObjectId("510f1b718474cd8af024e2d0"), "count" : 254 }
{ "_id" : ObjectId("510f1c8f8474cd8af024e2d1"), "count" : 34 }