Mongo数据操作

可以根据条件来更新指定的文档，但要注意查询条件的唯一性：

> db.tianyc04.remove()
> db.tianyc04.insert({name:'tyc',age:20})
> db.tianyc04.insert({name:'tyc',age:30})
> db.tianyc04.insert({name:'tyc',age:32})
> db.tianyc04.find()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "name" : "tyc", "age" : 20 }
{ "_id" : ObjectId("510c83b113d7e50c2281b049"), "name" : "tyc", "age" : 30 }
{ "_id" : ObjectId("510c83b313d7e50c2281b04a"), "name" : "tyc", "age" : 32 }
> x=db.tianyc04.findOne()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "name" : "tyc", "age" : 20 }
> x.age++
20
> x
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "name" : "tyc", "age" : 21 }
#按照name条件更新，将会更新所有记录。但x中已经包含了_id字段，这样会产生主键重复，所以mongo只会更新第一个。
> db.tianyc04.update({name:'tyc'}, x)
> db.tianyc04.find()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "name" : "tyc", "age" : 21 }
{ "_id" : ObjectId("510c83b113d7e50c2281b049"), "name" : "tyc", "age" : 30 }
{ "_id" : ObjectId("510c83b313d7e50c2281b04a"), "name" : "tyc", "age" : 32 }
#如果我更新第二条数据，会怎么样呢：
> x=db.tianyc04.findOne({age:30})
{ "_id" : ObjectId("510c83b113d7e50c2281b049"), "name" : "tyc", "age" : 30 }
> x.age++
30
> x
{ "_id" : ObjectId("510c83b113d7e50c2281b049"), "name" : "tyc", "age" : 31 }
> db.tianyc04.update({name:'tyc'},x)
> db.tianyc04.find()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "name" : "tyc", "age" : 21 }
{ "_id" : ObjectId("510c83b113d7e50c2281b049"), "name" : "tyc", "age" : 30 }
{ "_id" : ObjectId("510c83b313d7e50c2281b04a"), "name" : "tyc", "age" : 32 }
> db.getLastError()
null
#可以看到第二条数据并没有被更新掉。因为mongo会首先匹配到第一条记录，尝试将其更新为x，但此时会与第二条记录产生主键重复，所以mongo会直接退出，且没有提示错误。
#下面我按照_id来更新第二条记录，这次就更新正常了：
> db.tianyc04.update({_id:ObjectId("510c83b113d7e50c2281b049")},x)
> db.tianyc04.find()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "name" : "tyc", "age" : 21 }
{ "_id" : ObjectId("510c83b113d7e50c2281b049"), "name" : "tyc", "age" : 31 }
{ "_id" : ObjectId("510c83b313d7e50c2281b04a"), "name" : "tyc", "age" : 32 }
>

下面再无聊地使用tcy条件连续更新一下，就看到mongo的更新流程了：
> db.tianyc04.update({name:'tyc'},{name:'new_line'})
> db.tianyc04.find()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "name" : "new_line" }
{ "_id" : ObjectId("510c83b113d7e50c2281b049"), "name" : "tyc", "age" : 31 }
{ "_id" : ObjectId("510c83b313d7e50c2281b04a"), "name" : "tyc", "age" : 32 }
> db.tianyc04.update({name:'tyc'},{xjbu:'bengcaca'})
> db.tianyc04.find()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "name" : "new_line" }
{ "_id" : ObjectId("510c83b113d7e50c2281b049"), "xjbu" : "bengcaca" }
{ "_id" : ObjectId("510c83b313d7e50c2281b04a"), "name" : "tyc", "age" : 32 }
> db.tianyc04.update({name:'tyc'},{tonight:'papapa'})
> db.tianyc04.find()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "name" : "new_line" }
{ "_id" : ObjectId("510c83b113d7e50c2281b049"), "xjbu" : "bengcaca" }
{ "_id" : ObjectId("510c83b313d7e50c2281b04a"), "tonight" : "papapa" }
>

总结：更新时的查询条件建议选择_id。

除了查询条件，还可以使用修改器对文档进行更新。

1. $inc

> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "name" : "xtt", "age" : 11 }
> db.tianyc03.update({name:'xtt',age:11},{'$inc':{age:5}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "name" : "xtt", "age" : 16 }

#$inc还可以添加列。

> db.tianyc04.find()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "wc" : 1 }
> db.tianyc04.update({wc:1},{$inc:{score:50}})
> db.tianyc04.find()
{ "_id" : ObjectId("510c83ad13d7e50c2281b048"), "score" : 50, "wc" : 1 }
>

2. $set

用来指定一个键的值，若该键不存在，则创建。如果需要删除该键，使用$unset。

#新增加列sex
> db.tianyc03.update({name:'xtt',age:16},{$set:{sex:'m'}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "name" : "xtt", "sex" : "m" }
#修改列sex
> db.tianyc03.update({name:'xtt',age:16},{$set:{sex:'male'}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "name" : "xtt", "sex" : "male" }
#改变列sex数据类型
> db.tianyc03.update({name:'xtt',age:16},{$set:{sex:1}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "name" : "xtt", "sex" : 1 }
#删除列sex
> db.tianyc03.update({name:'xtt',age:16},{$unset:{sex:1}})
> db.tianyc03.find()
{ "_id" : ObjectId("50ea6b6f12729d90ce6e341b"), "age" : 16, "name" : "xtt" }

 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" }
>