批量更新mongodb

db.trains.find({}).forEach(function (x) {
    let reward = parseInt(x.reward, 10);
    db.trains.updateOne({ _id: x._id }, { "$set": { "reward": reward } });
});
db.myCollection.updateMany(
    {}, // 选择所有文档
    [
        {
            $set: {
                myField: { $toLong: "$dateField" } // 将 dateField 转换为毫秒级时间戳
            }
        }
    ]
)