MongoDB学习收拾之更新

Mongodb更新有两个命令：一个是update,另一个是save

update命令：
        db.collection.update(criteria,objNew,upsert,multi)
        参数说明：
        1）criteria：查询条件，类似于update语句内where后面的内容
        2）objNew：update的对象和一些更新的操作符(如$、$inc等)，也可以理解为关系型数据库update语句内set后面的内容
        3）upsert：如果不存在update的纪录，是否插入objNew这个新的document。true为插入，默认是false，不插入
        4）multi：默认是false,只更新找到的第一条纪录，如果为true,按条件查出来的多条纪录全部更新。

测试：
        1）准备数据：
                { "_id" : ObjectId("4fe0595216c38fae7549540f"), "count" : 2, "test2" : "t12" }
                { "_id" : ObjectId("4fe0595816c38fae75495410"), "count" : 3, "test2" : "t12" }
        2）测试更新count > 1 的纪录的test2的值为OK1，没有加入multi值
                db.t1.update({"count":{$gt:1}},{$set:{"test2":"OK1"}})
                更新后
                { "_id" : ObjectId("4fe0595216c38fae7549540f"), "count" : 2, "test2" : "OK1" }
                { "_id" : ObjectId("4fe0595816c38fae75495410"), "count" : 3, "test2" : "t12" }
                只更新了一条数据，是因为multi默认值都是false
        3）测试更新count > 1 的纪录的test2的值为OK2，加入multi               
                db.t1.update({"count":{$gt:1}},{$set:{"test2":"OK2"}},false,true)
                更新后
                { "_id" : ObjectId("4fe0595216c38fae7549540f"), "count" : 2, "test2" : "OK2" }
                { "_id" : ObjectId("4fe0595816c38fae75495410"), "count" : 3, "test2" : "OK2" }       
        4）测试更新count > 4 的纪录的test2的值为OK， upsert:true              
                db.t1.update({"count":{$gt:5}},{$set:{"test5":"OK"}},true,false)
                更新后
                { "_id" : ObjectId("4fe0595216c38fae7549540f"), "count" : 2, "test2" : "OK2" }
                { "_id" : ObjectId("4fe0595816c38fae75495410"), "count" : 3, "test2" : "OK2" }
                { "test5" : "OK" }

save命令：
        db.collection.save(obj)
        obj：要更新的纪录，只能试单挑纪录，如果collection没有存在与obj一样的id，则添加一条记录，否则更新

数据更新操作符
        1）$inc
                用法：{$inc:{field:value}},对一个数字字段的某个field增加value
                更新前：{ "_id" : ObjectId("4fe096e88a6e072b231ca5c9"), "name" : "liangzhangping", "age" : 30 }
                操作：db.t3.update({name:"liangzhangping"},{$inc:{age:5}})
                更新后：{ "_id" : ObjectId("4fe096e88a6e072b231ca5c9"), "name" : "liangzhangping", "age" : 35 }
        2）$set
                用法：{$set:{field:value}},类似于SQL语法中“set field=value”
                更新前：{ "_id" : ObjectId("4fe096e88a6e072b231ca5c9"), "name" : "liangzhangping", "age" : 30 }
                操作：db.t3.update({name:"liangzhangping"},{$set:{age:28}})
                更新后：{ "_id" : ObjectId("4fe096e88a6e072b231ca5c9"), "name" : "liangzhangping", "age" : 28 }
        3）$unset
                用法：{$unset:{field:1}},删除字段，类似于SQL语法中删除列
                更新前：{ "_id" : ObjectId("4fe096e88a6e072b231ca5c9"), "name" : "liangzhangping", "age" : 30 }
                操作：db.t3.update({name:"liangzhangping"},{$unset:{age:1}})
                更新后：{ "_id" : ObjectId("4fe096e88a6e072b231ca5c9"), "name" : "liangzhangping" }
        4）$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
                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 }
                操作：db.t3.update({"userid":3},{$pop:{name:-1}})
                更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "lzp", "xiaoping", "N1", "N2" ], "userid" : 3 }               
                操作：db.t3.update({"userid":3},{$pop:{name:1}})
                更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "lzp", "xiaoping", "N1" ], "userid" : 3 }
        8）$pull
                用法：{$pull:{field:value}},从数组filed内删除一个等于value的值
                更新前：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "lzp", "xiaoping", "N1" ], "userid" : 3 }
                操作：db.t3.update({"userid":3},{$pull:{name:"N1"}})
                更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "lzp", "xiaoping" ], "userid" : 3 }    
        9）$pullAll
                用法：{$pullAll:{field:value_array}},用法同$pull一样，可以一次删除数组内的多个值
                更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ "lzp", "xiaoping" ], "userid" : 3 }
                操作：db.t3.update({"userid":3},{$pullAll:{name:["lzp", "xiaoping"]}})
                更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ ], "userid" : 3 }     
        10）$rename
                用法：{$rename:{old_field_name:new_field_name}},完成字段的重命名
                更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "name" : [ ], "userid" : 3 }  
                操作：db.t3.update({"userid":3},{$rename:{name:"alias"}})
                更新后：{ "_id" : ObjectId("4fe098f08a6e072b231ca5ca"), "alias" : [ ], "userid" : 3 }