查找包含特定字段的MongoDB文档？

2026-06-04 1 花语

要查找包含特定字段的文档，请使用$exists。让我们创建一个包含文档的集合-

> db.demo247.insertOne({"ClientDetails":[{"ClientFirstName":"Chris","ClientAge":34}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e46b2a31627c0c63e7dba69") } >db.demo247.insertOne({"ClientDetails":[{"ClientFirstName":"John","ClientLastName":"Smith","ClientAge":31}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e46b2be1627c0c63e7dba6a") } > db.demo247.insertOne({"ClientDetails":[{"ClientFirstName":"David","ClientAge":33}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e46b2cd1627c0c63e7dba6b") } >db.demo247.insertOne({"ClientDetails":[{"ClientFirstName":"David","ClientLastName":"Miller","ClientAge":31}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e46b2de1627c0c63e7dba6c") }

在find()方法的帮助下显示集合中的所有文档-

> db.demo247.find().pretty();

这将产生以下输出-

{ "_id" : ObjectId("5e46b2a31627c0c63e7dba69"), "ClientDetails" : [ { "ClientFirstName" : "Chris", "ClientAge" : 34 } ] } { "_id" : ObjectId("5e46b2be1627c0c63e7dba6a"), "ClientDetails" : [ { "ClientFirstName" : "John", "ClientLastName" : "Smith", "ClientAge" : 31 } ] } { "_id" : ObjectId("5e46b2cd1627c0c63e7dba6b"), "ClientDetails" : [ { "ClientFirstName" : "David", "ClientAge" : 33 } ] } { "_id" : ObjectId("5e46b2de1627c0c63e7dba6c"), "ClientDetails" : [ { "ClientFirstName" : "David", "ClientLastName" : "Miller", "ClientAge" : 31 } ] }

以下是查找包含特定字段的文档的查询-

> db.demo247.find({"ClientDetails.ClientLastName":{$exists:true}});

这将产生以下输出-

{ "_id" : ObjectId("5e46b2be1627c0c63e7dba6a"), "ClientDetails" : [ { "ClientFirstName" : "John", "ClientLastName" : "Smith", "ClientAge" : 31 } ] } { "_id" : ObjectId("5e46b2de1627c0c63e7dba6c"), "ClientDetails" : [ { "ClientFirstName" : "David", "ClientLastName" : "Miller", "ClientAge" : 31 } ] }