MongoDB学习整理之更新(3)

来源：未知责任编辑：责任编辑发表时间:2014-04-20 03:42　点击:次

4）$push

用法：{$push:{field:value}},把value追加到field里。field一定是数组类型，如果field不存在，会新增一个

更新前：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "userid" : 3, "name" : [ "liangzhangping", "lzp" ] }

操作：db.t3.update({"userid":3},{$push:{name:"xiaoping"}})

更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "liangzhangping", "lzp", "xiaoping" ], "userid" : 3 }

5）$pushAll

用法：{$push:{field:value_array}},用法同$push一样，只是$pushAll一次可以追加多个值到一个数组字段内

更新前：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "liangzhangping", "lzp", "xiaoping" ], "userid" : 3 }

操作：db.t3.update({"userid":3},{$pushAll:{name:["N1","N2"]}})

更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "liangzhangping", "lzp", "xiaoping", "N1", "N2" ], "userid" : 3 }

6）$addToSet www.2cto.com

用法：{$addToSet:{field:value}},加一个值到数组内，而且只有当这个值不在数组内才增加

更新前：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "liangzhangping", "lzp", "xiaoping", "N1", "N2" ], "userid" : 3 }

操作：db.t3.update({"userid":3},{$addToSet:{name:"N1"}})

更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "liangzhangping", "lzp", "xiaoping", "N1", "N2" ], "userid" : 3 }

7）$pop

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

更新前：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "liangzhangping", "lzp", "xiaoping", "N1", "N2" ], "userid" : 3 }