MongoDB distinct aggregation

Question

I\'m working on a query to find cities with most zips for each state:

db.zips.distinct(\"state\", db.zips.aggregate([ {$group:{_id:{state:\"$state\", city:\"         


        

Answer 1

SQL Query: (group by & count of distinct)

select city,count(distinct(emailId)) from TransactionDetails group by city;

Equivalent mongo query would look like this:

db.TransactionDetails.aggregate([ 
{$group:{_id:{"CITY" : "$cityName"},uniqueCount: {$addToSet: "$emailId"}}},
{$project:{"CITY":1,uniqueCustomerCount:{$size:"$uniqueCount"}} } 
]);