Insert document into mongodb from existing table - mongodb

Question

I am trying to write a query in mongo that will create a new table, loop through my data set, and insert the TopExecutiveTitle into the new table. I also would like it to keep count of each position and only insert a position into the table when it is new.
This is what I have so far. This code loops through my table and inserts the TopExectuiveTitle into a new table. However, it does not group them together and keep count. How do I write my query so that it will?
db.car.find().forEach( function (x) {
db.TopExecutiveTable.insert({Topexecutivetitle: x.Topexecutivetitle})
});
Here is a sample of a document in my database.
{
"_id" : ObjectId("5a22c8e562c2e489c5df70fa"),
"2016rank" : 1,
"Dealershipgroupname" : "AutoNation Inc.?",
"Address" : "200 S.W. 1st Ave.",
"City/State/Zip" : "Fort Lauderdale, FL 33301",
"Phone" : "[phone]",
"Companywebsite" : "www.autonation.com",
"Topexecutive" : "Mike Jackson",
"Topexecutivetitle" : "chairman & CEO",
"Totalnewretailunits" : "337,622",
"Totalusedunits" : "225,713",
"Totalfleetunits" : 3,
"Totalwholesaleunits" : "82,342",
"Total_units" : "649,415",
"Total_number_of _dealerships" : 260,
"Grouprevenuealldepartments*" : "$21,609,000,000",
"2015rank" : 1
}
The result I would like is something like this
"Topexecutivetitle" : "chairman & CEO"
"Count" : 3
"Topexecutivetitle" : "president"
"Count" : 7
}

Answer 1

To do this you need to use the aggregate function of mongo, something like this:
db.car.aggregate([
{
$group:{
_id:"$Topexecutivetitle",
count:{$sum:1}
}
},
{
$project:{
Topexecutivetitle:"$_id",
count:1,
_id:0
}
},
{
$out:"result"
}])
This will give you your desired output and store it into a new collection "result":
{
"_id" : "president",
"count" : 1.0
},
{
"_id" : "chairman & CEO",
"count" : 3.0
}