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728. Date Differences

Learn how to calculate the difference between two dates using SQL date functions.

📘 Lesson 727 of 728 ⏱ 8 min 🎯 Intermediate

Date difference functions calculate the number of days, months, years, hours, or other time units between two dates. Different database systems provide functions such as DATEDIFF() or date arithmetic to perform these calculations.

Businesses frequently calculate employee experience, customer age, delivery duration, project timelines, payment due dates, and order processing time using date differences.

An HR department calculates the number of years an employee has worked in the company based on the joining date and today's date.

SQL 
SELECT
    EmployeeName,
    JoiningDate,
    DATEDIFF(YEAR, JoiningDate, GETDATE()) AS ExperienceYears
FROM Employees;

Date difference calculations are used in payroll systems, banking, insurance, logistics, healthcare, customer relationship management, project management, and business reporting.

  • Calculates the difference between two dates.
  • Supports days, months, and years.
  • Commonly uses the DATEDIFF() function.
  • Useful for age and experience calculations.
  • Helps analyze business timelines.
  • Widely used in reporting and analytics.
  • Available with database-specific syntax.
Which SQL function is commonly used to calculate the difference between two dates?

DATEDIFF() is commonly used in SQL Server to calculate the difference between two dates.

Give one business example of using date differences.

Calculating employee experience, customer age, loan duration, or delivery time are common business examples.

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