Calculate Date Differences Across Databases

The DATEDIFF function helps SQL users compute the difference between two dates. While widely supported, its syntax and behavior vary across databases.

This article provides a quick look at how DATEDIFF works and highlights database-specific differences.

DATEDIFF usage

To find the difference between two dates, the function follows this pattern:

SELECT DATEDIFF(year, '2023-01-01', '2024-01-01');

This query returns 1.

However, not all databases support this syntax. Some return only the difference in days, while others require specifying a date unit.

Databases that support DATEDIFF

• SQL Server allows choosing datepart (years, months, days).

• MySQL & MariaDB returns only days.

• Snowflake & Redshift require specifying the date unit.

Databases without DATEDIFF

For databases without a direct DATEDIFF function, alternatives exist:

• PostgreSQL uses AGE() instead of DATEDIFF.

• Oracle uses MONTHS_BETWEEN() to find monthly differences.

• SQLite uses strftime() to extract date parts.

FAQ

What does DATEDIFF do?

It calculates the difference between two date values.

Does every SQL database support DATEDIFF?

No, some databases like PostgreSQL and Oracle require workarounds.

Can I use DATEDIFF for time values?

Yes, some databases allow using hours, minutes, or seconds.

Does DATEDIFF consider leap years?

Yes, in most databases, the function accounts for leap years.

Conclusion

Knowing how DATEDIFF functions across SQL databases ensures accurate date calculations. Explore the full guide Understanding the DATEDIFF SQL Function: A Comprehensive Guide for more details.