> db.mytest.update({_id:15},{$set:{array:["aaa","bbb"]}})

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "aaa", "bbb" ], "count" : 15, "name" : "ok123" }

使用push追加数据：

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> db.mytest.update({_id:15},{$push:{array:"ccc"}})

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "aaa", "bbb", "ccc" ], "count" : 15, "name" : "ok123" }

push一次只能追加一个值，如果需要追加多个值，则需要使用$pushAll：

[plain]

> db.mytest.update({_id:15},{$pushAll:{array:["ddd","eee","fff"]}})

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "aaa", "bbb", "ccc", "ddd", "eee", "fff" ], "count" : 15, "name" : "ok123" }

8). $addToSet

用法：{$addToSet:{field:value}}

增加一个值到数组内，而且只有当这个值不在数组内才增加：

[plain]

> db.mytest.update({_id:15},{$addToSet:{array:"123"}})

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "aaa", "bbb", "123" ], "array2" : [ "mmm", "nnn"], "count" : 15, "name" : "ok123" }

> db.mytest.update({_id:15},{$addToSet:{array:"aaa"}})

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "aaa", "bbb", "123" ], "array2" : [ "mmm", "nnn"], "count" : 15, "name" : "ok123" }

9). $pop

删除数组内的一个值，删除最后一个值：{$pop:{field:1}} ，删除第一个值：{$pop:{field:-1}}

[plain]

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "aaa", "bbb", "123" ], "array2" : [ "mmm", "nnn"], "count" : 15, "name" : "ok123" }

> db.mytest.update({_id:15},{$pop:{array:1}})

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "aaa", "bbb" ], "array2" : [ "mmm", "nnn" ], "count" : 15, "name" : "ok123" }

10). $pull

用法：$pull:{field:value} 从数组中删除一个等于value的值：

[plain]

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "aaa", "bbb" ], "array2" : [ "mmm", "nnn" ], "coun

t" : 15, "name" : "ok123" }

> db.mytest.update({_id:15},{$pull:{array:"aaa"}})

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "bbb" ], "array2" : [ "mmm", "nnn" ], "count" : 15,

"name" : "ok123" }

11). $pullAll

用法同$pull，可以一次删除数组内的多个值：

[plain]

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "bbb" ], "array2" : [ "mmm", "nnn" ], "count" : 15,"name" : "ok123" }

> db.mytest.update({_id:15},{$pullAll:{array2:["mmm","nnn"]}})

> db.mytest.find({_id:15})

{ "_id" : 15, "array" : [ "bbb" ], "array2" : [ ], "count" : 15, "name" : "ok123" }

12). $

可以理解为数组定位器，看一个官方文档的例子：

[plain]

> t.find()

{ "_id" : ObjectId("4b97e62bf1d8c7152c9ccb74"), "title" : "ABC", "comments" : [ { "by" : "joe", "votes" : 3 }, { "by" : "jane", "votes" : 7 } ] }

> t.update( {'comments.by':'joe'}, {$inc:{'comments.$.votes':1}})

> t.find()

{ "_id" : ObjectId("4b97e62bf1d8c7152c9ccb74"), "title" : "ABC", "comments" : [ { "by" : "joe", "votes" : 4 }, { "by" : "jane", "votes" : 7 } ] }

需要注意的是，$只会找到第一条数组项，后面的就不管了：

[plain]

> db.mytest.find({_id:16})

{ "_id" : 16, "x" : [ 1, 2, 3, 1 ] }

> db.mytest.update({x:1},{$inc:{"x.$":1}})

> db.mytest.find({_id:16})

{ "_id" : 16, "x" : [ 2, 2, 3, 1 ] }

还有一点需要注意，当$配合$unset使用的时候，会留下一个null的数组项，这个问题可以使用{$pull:{x:null}}解决：

[plain]

> db.mytest.find({_id:16})

{ "_id" : 16, "x" : [ 2, 2, 3, 1 ] }

> db.mytest.update({x:3},{$unset:{"x.$":1}})

> db.mytest.find({_id:16})

{ "_id" : 16, "x" : [ 2, 2, null, 1 ] }