This guide is specifically for PostgreSQL syntax.

How to Calculate Date Difference in SQL

Calculate the difference between two dates in days, months, or years.

Quick Answer

SELECT DATEDIFF(end_date, start_date) FROM table;

Explanation

DATEDIFF calculates the difference between dates. Syntax varies by database. MySQL uses DATEDIFF(date1, date2), SQL Server uses DATEDIFF(unit, date1, date2).

Query Variants

Mysql Days

SELECT DATEDIFF(end_date, start_date) as days FROM projects;

Postgres Days

SELECT end_date - start_date as days FROM projects;

Sqlserver

SELECT DATEDIFF(day, start_date, end_date) as days FROM projects;

Months

SELECT TIMESTAMPDIFF(MONTH, start_date, end_date) as months FROM projects;

Pro Tips

Check your database's date function syntax
Consider timezone issues
Use appropriate units (day, month, year)

Related SQL Queries

Continue learning with more SQL query examples:

PostgreSQL-Specific Notes

This page covers PostgreSQL syntax. Other databases may have different syntax for similar operations.

PostgreSQL: How to Calculate Date Difference in SQL