解决 MongoDb 中“多更新仅适用于 $ 运算符”的问题？
您可以为此使用$set运算符。语法如下-
db.yourCollectionName.update({ }, {'$set': "yourFieldName": "yourValue" }, false, true);为了理解上述语法，让我们用文档创建一个集合。使用文档创建集合的查询如下-
> db.unconditionalUpdatesDemo.insertOne({"ClientName":"Larry","ClientAge":24});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8eb7372f684a30fbdfd557")
}
> db.unconditionalUpdatesDemo.insertOne({"ClientName":"Mike","ClientAge":26});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8eb73f2f684a30fbdfd558")
}
> db.unconditionalUpdatesDemo.insertOne({"ClientName":"Sam","ClientAge":27});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8eb7462f684a30fbdfd559")
}
> db.unconditionalUpdatesDemo.insertOne({"ClientName":"Carol","ClientAge":29});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8eb7502f684a30fbdfd55a")
}在find()方法的帮助下显示集合中的所有文档。查询如下-
> db.unconditionalUpdatesDemo.find().pretty();
以下是输出-
{
"_id" : ObjectId("5c8eb7372f684a30fbdfd557"),
"ClientName" : "Larry",
"ClientAge" : 24
}
{
"_id" : ObjectId("5c8eb73f2f684a30fbdfd558"),
"ClientName" : "Mike",
"ClientAge" : 26
}
{
"_id" : ObjectId("5c8eb7462f684a30fbdfd559"),
"ClientName" : "Sam",
"ClientAge" : 27
}
{
"_id" : ObjectId("5c8eb7502f684a30fbdfd55a"),
"ClientName" : "Carol",
"ClientAge" : 29
}这是无条件更新的查询-
> db.unconditionalUpdatesDemo.update({ }, {'$set': {"ClientName": "Robert" }}, false, true);
WriteResult({ "nMatched" : 4, "nUpserted" : 0, "nModified" : 4 })让我们在帮助下检查集合中的文档find()。查询如下-
> db.unconditionalUpdatesDemo.find().pretty();
以下是输出-
{
"_id" : ObjectId("5c8eb7372f684a30fbdfd557"),
"ClientName" : "Robert",
"ClientAge" : 24
}
{
"_id" : ObjectId("5c8eb73f2f684a30fbdfd558"),
"ClientName" : "Robert",
"ClientAge" : 26
}
{
"_id" : ObjectId("5c8eb7462f684a30fbdfd559"),
"ClientName" : "Robert",
"ClientAge" : 27
}
{
"_id" : ObjectId("5c8eb7502f684a30fbdfd55a"),
"ClientName" : "Robert",
"ClientAge" : 29
}