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let db = new webdb.Db('mydb', { people: ['age'] });
let people = db.collection('people');

let docs = [
    { name: 'Frank', age: 20 },
    { name: 'Thomas', age: 33 },
    { name: 'Todd', age: 33 },
    { name: 'John', age: 28 },
    { name: 'Peter', age: 33 },
    { name: 'George', age: 28 }
];

people.insert(docs).then(() => {
    return people.find({
        name: { $ne: 'John' },
        age: { $gt: 20 }
    }).group({
        _id: { age: '$age' },
        count: { $sum: 1 }
    }).project({
        _id: 0,
        age: '$_id.age'
    }).sort({
        age: -1
    }).forEach(doc => console.log('doc:', doc));
}).catch(error => console.error(error));

Document Language Operators

Filter Operators

The following filter operators are supported: $and, $or, $not, $nor, $eq, $ne, $gt, $gte, $lt, $lte, $in, $nin, $elemMatch, $regex, and $exists.

Expression Operators

Expression operators can be used in combination with the group and projection operators.

The following expression operators are supported: $literal, $add, $subtract, $multiply, $divide, $mod, $abs, $ceil, $floor, $ln, $log10, $pow, $sqrt, $trunc, $concat, $toLower, $toUpper, $concatArrays, $dayOfMonth, $year, $month, $hour, $minute, $second, and $millisecond.

Update Operators

The following update operators are supported: $set, $unset, $rename, $inc, $mul, $min, $max, $push, $pop, $pullAll, $pull, and $addToSet.

Group Operators

The following group operators are supported: $sum, $avg, $min, $max, $push, and $addToSet.

Aggregation Pipeline Stages

支持以下聚合管道阶段：“$match”、“$project”、“$group”、“$unwind”、“$sort”、“$skip”和“$limit”。