Date Functions (DATEADD, DATEDIFF, EXTRACT)

SQL includes useful functions to work with dates and times.

Common Date Functions

• DATEADD(unit, number, date) — Adds a specified number of units (days, months, years) to a date
• DATEDIFF(unit, start_date, end_date) — Calculates the difference between two dates in specified units
• EXTRACT(part FROM date) — Extracts part of a date like year, month, or day

Example: Find Students Who Joined Over 30 Days Ago

SELECT * FROM students
WHERE DATEDIFF(day, join_date, CURRENT_DATE) > 30;

This finds students whose join_date is more than 30 days before today.

Date functions help analyze timelines, calculate ages, filter date ranges, and more.

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