Q.Can we use arithmetic operators (+, -. *, or /) on date functions?

Date Arithmetic Operators

Date arithmetic in SQL and pandas follows specific rules because dates are not simple numbers—they represent points in time or intervals. You cannot apply all four arithmetic operators freely; only addition and subtraction make logical sense, and even those require careful pairing of operands.

SQL (MySQL / standard SQL)

Addition (+) and Subtraction (-) are supported, but only in meaningful combinations:

• Date ± integer: adds or subtracts days. For example, DATE '2024-01-15' + 7 yields 2024-01-22.
• Date ± INTERVAL: adds or subtracts a time span. DATE '2024-01-15' + INTERVAL 2 MONTH gives 2024-03-15.
• Date - Date: returns the difference in days (or a time interval, depending on the DBMS). DATE '2024-01-20' - DATE '2024-01-15' yields 5.

Multiplication (*) and Division (/) are not defined for dates. Multiplying a date by 3 or dividing it by 2 has no temporal meaning, so these operations will throw a type error.

Python pandas

The same logic applies. A datetime64 column or Timestamp object supports:

• Addition/subtraction with Timedelta or DateOffset: df['date'] + pd.Timedelta(days=5) shifts every date forward by five days.
• Subtraction between two dates: df['end'] - df['start'] produces a Timedelta series representing the duration.

Multiplication and division of dates themselves remain undefined. You can multiply or divide a Timedelta (a duration) by a scalar—pd.Timedelta(days=10) * 2 is valid and yields 20 days—but that is arithmetic on the interval, not the date.

import pandas as pd

df = pd.DataFrame({'start': pd.to_datetime(['2024-01-10', '2024-02-15']),
                   'end':   pd.to_datetime(['2024-01-20', '2024-03-01'])}) …

Date arithmetic is fundamentally about measuring or shifting time. When you think about what makes sense with dates, addition and subtraction have clear interpretations — adding days to a date moves it forward, subtracting two dates gives you the interval between them — but multiplying or dividing a date has no logical meaning. You cannot "multiply Tuesday by 3" or "divide January 15th by 2."

Which operators work with dates?

Addition (+)

You can add an interval (a number of days, months, years, or a timedelta) to a date to get a new date.

SELECT ADDDATE('2024-01-15', INTERVAL 10 DAY);
-- Result: 2024-01-25

import pandas as pd
from datetime import timedelta

date = pd.to_datetime('2024-01-15')
new_date = date + timedelta(days=10)
print(new_date)
# Output: 2024-01-25 00:00:00

Subtraction (-)

You can subtract an interval from a date (to get an earlier date), or subtract one date from another (to get the difference in days/time).

SELECT DATEDIFF('2024-01-25', '2024-01-15');
-- Result: 10 (days between the two dates)

date1 = pd.to_datetime('2024-01-25')
date2 = pd.to_datetime('2024-01-15')
difference = date1 - date2
print(difference.days)
# Output: 10

In pandas, subtracting two datetime objects gives you a Timedelta object, from which you can extract .days, .seconds, etc.

Multiplication (*) and Division (/)

These operators are not defined for date or datetime objects. A date represents a point in time, not a quantity you can scale. Attempting to multiply or divide dates will raise a TypeError in Python or a syntax error in SQL.

# This will FAIL:
date = pd.to_datetime('2024-01-15')
result = date * 2  # TypeError: unsupported operand type(s)
``` …