SQL for Analytics - lesson 1 | HackIndia Skills

Key point

One idea

Good SQL starts before SQL. First write the product question so clearly that another person can build the same query.

A clear question names the metric, who it is about, the event or table, the time period, and how the result should be grouped.

Why this matters

Most bad analytics projects do not fail because of syntax. They fail because the question is vague.

“How is our app doing?” can mean signups, payments, retention, active users, or revenue. Each needs a different query and a different answer.

Your to-do

Question checklist

Do each one yourself, then tap it to tick it off. The ticks are only a checklist for you: they are not marked or scored.

Name the decision the answer will help with.
Choose one metric, like signups, orders, revenue, or completion rate.
Define the users or rows included in the answer.
Set a time range, like last 7 days or January 2026.
Choose the breakdown, like day, city, plan, device, or college.

0 of 5 done

Example

Make it queryable

Here is a weak question and a better version for a campus food ordering app.

The better version is ready for SQL because it tells you what to count and how to group it.

Weak: Are users ordering food?

Better: For users in Bengaluru, how many paid orders were placed each day from 1 Jan 2026 to 7 Jan 2026?

Metric: paid orders
Rows included: orders where status = 'paid'
Time range: 2026-01-01 to 2026-01-07
Group by: order date
Filter: city = 'Bengaluru'

Tip

Use AI well

You can ask ChatGPT, Gemini, or Claude to improve your question before writing SQL. Do not ask it to guess your business rules.

Paste your rough question and ask: “Rewrite this as a SQL-ready analytics question. List metric, filters, date range, grouping, and assumptions.” Then check every assumption yourself.

Common mistake

Avoid hidden definitions

Words like active, retained, converted, paid, and new look simple but need rules.

For example, “active user” could mean opened the app, viewed a product, placed an order, or paid. Pick one definition and write it down.