Accumulator Operators
$sum, $avg, $min, $max, NUMERIC, AGGREGATIONS, ke, liye, HAIN. $push, HAR, GROUP, ke, DOCUMENTS, ki, EK, VALUE, ko, ARRAY, mein, COLLECT, karta hai (DUPLICATES, ke, saath). $addToSet, SAME, kaam, karta hai, LEKIN, DUPLICATES, REMOVE, kar, deta hai.
$first aur $last, (WITH, $sort, se, PEHLE) EK, GROUP, ke, FIRST/LAST, DOCUMENT, ki, VALUE, RETURN, karte, HAIN — jaise, HAR, CUSTOMER, ka, MOST, RECENT, ORDER, DHOONDHNE, ke, liye.
db.orders.aggregate([
{ $group: {
_id: "$customerId",
totalSpent: { $sum: "$amount" },
avgOrder: { $avg: "$amount" },
products: { $addToSet: "$productName" }, // unique products
allOrderIds: { $push: "$_id" } // saare order IDs
}}
]);- $sum, $avg, $min, $max = numeric aggregations
- $push = array collect (WITH duplicates), $addToSet = unique values
- $first/$last = sorted, group, ke, first/last, document, ki, value
$stdDevPop, aur, $stdDevSamp, statistical, ANALYSIS, ke, liye, standard, deviation, calculate, karte, hain — data, science, aur, analytics, dashboards, ke, liye, useful, HAIN.
{ $group: { _id: "$category", priceStdDev: { $stdDevPop: "$price" } } }$sum, $avg, jaise, accumulators, $group, ke, ALAWA, $bucket, aur, window, functions, ($setWindowFields) mein, bhi, use, kiye, ja, sakte, hain — RUNNING, TOTALS, YA, MOVING, AVERAGES, calculate, karne, ke, liye.