SightQL Daily Digest

💡 Tip of the Day

BEGINNER SQL

The one SQL query every business owner should know

If you learn nothing else about SQL, learn this pattern. It answers the question: "How is my business doing this month compared to last month?"

SELECT DATE_TRUNC('month', order_date) AS month, COUNT(*) AS orders, SUM(total) AS revenue, ROUND(AVG(total), 2) AS avg_order FROM orders WHERE order_date >= CURRENT_DATE - INTERVAL '2 months' GROUP BY 1 ORDER BY month DESC;

Why this matters: Month-over-month comparison is the single most powerful way to spot trends. Revenue up 15%? Something is working. Down 10%? Investigate immediately. No spreadsheet pivots needed.

🏪 Industry Spotlight: E-Commerce

E-COMMERCE

Your repeat purchase rate is more important than new sales

Most e-commerce businesses obsess over customer acquisition. But the math is clear:

5-15%

Average repeat purchase rate

25-40%

Top performers achieve this

5-25×

Cheaper to retain than acquire

67%

More spend from repeat customers

Track this weekly:

-- What % of this month's orders are from repeat buyers? SELECT COUNT(CASE WHEN order_count > 1 THEN 1 END)::float / COUNT(*) * 100 AS repeat_pct FROM ( SELECT customer_id, COUNT(*) AS order_count FROM orders WHERE created_at >= DATE_TRUNC('month', CURRENT_DATE) GROUP BY customer_id ) t;

If your repeat rate is below 20%, stop spending on ads and start spending on retention: email sequences, loyalty programs, better post-purchase experience.

🧠 Daily Data Quiz

You run a SaaS with 500 active subscribers at $49/mo. Your churn rate is 5%/month. How much new MRR do you need each month just to break even?

🛠️ Tool Spotlight

PostgreSQL: The database your business deserves

If you are still running your business on spreadsheets or SQLite, consider PostgreSQL:

Why PostgreSQL?

Free and open source
Handles millions of rows without breaking a sweat
Window functions for running totals, rankings, and trends
JSON support for flexible data (no strict schema needed)
Connects to every BI tool: Metabase, Superset, SightQL

Getting started: Supabase and Neon offer free PostgreSQL databases that you can set up in 2 minutes. No server management needed.

Want answers, not queries?
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