⏱️ DATEDIFF() – Calculate Days Between Two Dates in SQL

🔧 Quick Syntax

SELECT DATEDIFF(date1, date2);

This tells SQL:

“Tell me how many days are between date1 and date2.”

Note: SQL does date1 - date2 → so:

• If date1 is newer, the result is positive
• If date1 is older, the result is negative

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🧾 Here’s the Table You’re Working With

Your table is called orders:

id	customer	order_date
1	Fenn	2025-04-10
2	Milo	2025-04-14
3	Sora	2025-04-01
4	Lexa	2025-03-25
5	Tovi	2025-04-12

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✅ Suppose You Want to Know How Many Days Ago Each Order Was Placed

SELECT customer, DATEDIFF(CURDATE(), order_date) AS days_ago
FROM orders;

💡 Output (if today is 2025-04-14):

Fenn    → 4
Milo    → 0
Sora    → 13
Lexa    → 20
Tovi    → 2

This shows how many days have passed since each order was placed — great for time-based reporting.

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✅ Suppose You Want to See Orders Older Than 7 Days

SELECT *
FROM orders
WHERE DATEDIFF(CURDATE(), order_date) > 7;

💡 Output:

Sora
Lexa

Only those two orders are more than 7 days old — perfect for follow-up reminders, alerts, or overdue filters.

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🧃 Recap – What You Learned

• DATEDIFF() returns the number of days between two dates
• Positive if the first date is newer
• Use CURDATE() to compare with today
• Great for tracking age, delays, reminders, or due dates
• Works in SELECT, WHERE, or inside calculations