如何在MongoDB中更新多个文档？
您需要使用multi：true来更新多个文档。首先让我们创建一个包含文档的集合-
> db.multiUpdateDemo.insertOne({"ClientName":"John","ClientAge":29});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cda5bc0b50a6c6dd317adc8")
}
> db.multiUpdateDemo.insertOne({"ClientName":"Carol","ClientAge":31});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cda5bc1b50a6c6dd317adc9")
}
> db.multiUpdateDemo.insertOne({"ClientName":"John","ClientAge":39});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cda5bc3b50a6c6dd317adca")
}
> db.multiUpdateDemo.insertOne({"ClientName":"John","ClientAge":41});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cda5bc5b50a6c6dd317adcb")
}
> db.multiUpdateDemo.insertOne({"ClientName":"David","ClientAge":35});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cda5bc6b50a6c6dd317adcc")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.multiUpdateDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cda5bc0b50a6c6dd317adc8"),
"ClientName" : "John",
"ClientAge" : 29
}
{
"_id" : ObjectId("5cda5bc1b50a6c6dd317adc9"),
"ClientName" : "Carol",
"ClientAge" : 31
}
{
"_id" : ObjectId("5cda5bc3b50a6c6dd317adca"),
"ClientName" : "John",
"ClientAge" : 39
}
{
"_id" : ObjectId("5cda5bc5b50a6c6dd317adcb"),
"ClientName" : "John",
"ClientAge" : 41
}
{
"_id" : ObjectId("5cda5bc6b50a6c6dd317adcc"),
"ClientName" : "David",
"ClientAge" : 35
}以下是执行多次更新的查询。现在，使用以下查询，三个客户端的ClientName“John”将具有更新的年龄-
> db.multiUpdateDemo.update({'ClientName': 'John'}, {$set: {'ClientAge': 34}}, {multi: true});
WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })让我们再次检查文件-
> db.multiUpdateDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cda5bc0b50a6c6dd317adc8"),
"ClientName" : "John",
"ClientAge" : 34
}
{
"_id" : ObjectId("5cda5bc1b50a6c6dd317adc9"),
"ClientName" : "Carol",
"ClientAge" : 31
}
{
"_id" : ObjectId("5cda5bc3b50a6c6dd317adca"),
"ClientName" : "John",
"ClientAge" : 34
}
{
"_id" : ObjectId("5cda5bc5b50a6c6dd317adcb"),
"ClientName" : "John",
"ClientAge" : 34
}
{
"_id" : ObjectId("5cda5bc6b50a6c6dd317adcc"),
"ClientName" : "David",
"ClientAge" : 35
}