Common date calculations:

Adding or Subtracting Days:

Use the DATE_ADD or DATE_SUB functions to add or subtract days from a date:

                                  
                                    -- Adding 3 days to the current date
SELECT DATE_ADD(CURRENT_DATE, INTERVAL 3 DAY) AS future_date;

-- Subtracting 1 day from the current date
SELECT DATE_SUB(CURRENT_DATE, INTERVAL 1 DAY) AS past_date;
                                  
                                

Extracting Components of a Date:

Use the YEAR, MONTH, and DAY functions to extract the year, month, and day components from a date:

                                  
                                    SELECT
                                    YEAR(some_date_column) AS year,
                                    MONTH(some_date_column) AS month,
                                    DAY(some_date_column) AS day
                                FROM your_table;                                
                                  
                                

Formatting Dates:

Use the DATE_FORMAT function to format date values into a specific format:

                                
                                    SELECT
    some_date_column,
    DATE_FORMAT(some_date_column, '%Y-%m-%d') AS formatted_date
FROM your_table;
                                
                              

Calculating Date Differences:

Use the DATEDIFF function to calculate the difference between two dates in days:

                                  
                                    SELECT
    DATEDIFF(end_date_column, start_date_column) AS days_difference
FROM your_table;
                                  
                                

Calculating Age:

Use the TIMESTAMPDIFF function to calculate the age in years, months, or days:

                                  
                                    SELECT
    TIMESTAMPDIFF(YEAR, birth_date_column, CURRENT_DATE) AS age_in_years,
    TIMESTAMPDIFF(MONTH, birth_date_column, CURRENT_DATE) AS age_in_months,
    TIMESTAMPDIFF(DAY, birth_date_column, CURRENT_DATE) AS age_in_days
FROM your_table;
                                  
                                

Tips:

• Be aware of the date format used in your database, as it might affect date calculations.
• Understand the data types and functions supported by your specific database system (e.g., MySQL, PostgreSQL, SQL Server).
• Pay attention to time zones if your dates include time components.