MongoDB选择并连接字段

Question

I have a very basic question:

SELECT name, surname CONCAT(name, surname) AS name_surname from users;

How can I convert this SQL to MongoDB query?

During my search, I have decided that it is possible with aggregate framework due to concat , but what I received is only projection of concat(name, surname) not name , surname and concat(name, surname) .

Final thing I got is this query:

db.inroamers.find().forEach(
                 function(o) { 
                 print(o.LAC + '-' + o.CELL + ' ' + o.CHARGE + ' ' + o.WEEK);
               })

but it does not give me proper json array.

Any suggestions?

Answer 1

Use the aggregation operations as below:

db.collection.aggregate([
{$project:{"name_surname":{$concat:["$name","-","$surname"]},"name":1,"surname":1}}
])