如何在 MongoDB 集合中的每个文档中添加新字段?
mongodbdatabasebig data analytics更新于 2026/1/27 3:37:17
要如何在 MongoDB 集合中的每个文档中添加新字段，可以使用 $set 运算符。语法如下:
db.yourCollectionName.update({}, { $set: {"yourFieldName": yourValue}}, false, true);
为了理解上述语法，让我们创建一个包含一些文档的集合。创建包含文档的集合的查询如下:
>db.addNewFieldToEveryDocument.insertOne({"StudentName":"John","StudentAddress":"US
"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c6efc0b6fd07954a48906ae")
}
>db.addNewFieldToEveryDocument.insertOne({"StudentName":"David","StudentAddress":"U
K"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c6efc0b6fd07954a48906af")
}
>db.addNewFieldToEveryDocument.insertOne({"StudentName":"Carol","StudentAddress":"U
K"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c6efc0b6fd07954a48906b0")
}
>db.addNewFieldToEveryDocument.insertOne({"StudentName":"Bob","StudentAddress":"US"
});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c6efc0b6fd07954a48906b1")
}
使用 find() 方法显示集合中的所有文档。查询如下:
> db.addNewFieldToEveryDocument.find().pretty();
输出结果如下:
{
"_id" : ObjectId("5c6efc0b6fd07954a48906ae"),
"StudentName" : "John",
"StudentAddress" : "US"
}
{
"_id" : ObjectId("5c6efc0b6fd07954a48906af"),
"StudentName" : "David",
"StudentAddress" : "UK"
}
{
"_id" : ObjectId("5c6efc0b6fd07954a48906b0"),
"StudentName" : "Carol",
"StudentAddress" : "UK"
}
{
"_id" : ObjectId("5c6efc0b6fd07954a48906b1"),
"StudentName" : "Bob",
"StudentAddress" : "US"
}
以下是向每个文档添加新字段的查询:
> db.addNewFieldToEveryDocument.update({}, { $set: {"StudentAge": 24} }, false, true);
WriteResult({ "nMatched" : 4, "nUpserted" : 0, "nModified" : 4 })
上面，我们在每个文档中添加了一个新字段"StudentAge":24。让我们检查一下该字段"StudentAge":24 是否已成功添加到每个文档。查询如下:
> db.addNewFieldToEveryDocument.find().pretty();
输出结果如下:
{
"_id" : ObjectId("5c6efc0b6fd07954a48906ae"),
"StudentName" : "John",
"StudentAddress" : "US",
"StudentAge" : 24
}
{
"_id" : ObjectId("5c6efc0b6fd07954a48906af"),
"StudentName" : "David",
"StudentAddress" : "UK",
"StudentAge" : 24
}
{
"_id" : ObjectId("5c6efc0b6fd07954a48906b0"),
"StudentName" : "Carol",
"StudentAddress" : "UK",
"StudentAge" : 24
}
{
"_id" : ObjectId("5c6efc0b6fd07954a48906b1"),
"StudentName" : "Bob",
"StudentAddress" : "US",
"StudentAge" : 24
}
