MongoDB问题 -------------------------------------插入不重复数据

Myth丶恋晨 2022-03-26 09:25 194阅读 0赞

1.2 upsert

upsert可以指定如果数据存在就更新，不存在就创建数据。

> db.users.find({"name":"yoona"});
    > 
    > db.users.update({"name":"yoona"}, {name : "yoona", age:25, "school" : "xidian", type:1,  favorites: {artist : "Noguchi", food : "nougat"}, finished : [4, 5] }, {upsert:false});
    WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })

更新操作之前我们没有查询到yoona的任何信息，然后我们对其进行更新操作，并且upsert设置为false，表示如果更新的数据不存在，不走任何操作。更新之后，我们再次查询一下：

> db.users.find({"name":"yoona"});
    >

再次查询还是没有找到相应数据。我们设置upsert为true，表示如果数据存在则更新，如果不存在则创建该数据：

> db.users.update({"name":"yoona"}, {name : "yoona", age:25, "school" : "xidian", type:1,  favorites: {artist : "Noguchi", food : "nougat"}, finished : [4, 5] }, {upsert:true});
    WriteResult({
        "nMatched" : 0,
        "nUpserted" : 1,
        "nModified" : 0,
        "_id" : ObjectId("57c3ad26d2cc0133a95bc583")
    })
    > 
    > db.users.find({"name":"yoona"});
    { "_id" : ObjectId("57c3ad26d2cc0133a95bc583"), "name" : "yoona", "age" : 25, "school" : "xidian", "type" : 1, "favorites" : { "artist" : "Noguchi", "food" : "nougat" }, "finished" : [ 4, 5 ] }

参考：[https://www.cnblogs.com/jokerjason/p/7552667.html][https_www.cnblogs.com_jokerjason_p_7552667.html]

[https_www.cnblogs.com_jokerjason_p_7552667.html]: https://www.cnblogs.com/jokerjason/p/7552667.html