Insert/ Update random date in MySQL

You can get a random integer with this expression:

To obtain a random integer R in the range i <= R < j, use the expression FLOOR(i + RAND() * (j - i)). For example, to obtain a random integer in the range the range 7 <= R < 12, you could use the following statement:

SELECT FLOOR(7 + (RAND() * 5));

https://dev.mysql.com/doc/refman/8.0/en/mathematical-functions.html#function_rand

Use that to generate a random number of days, hours or minutes (depending on the resolution) and add that number to current date.

Full expression would be:

-- Date only
SELECT CURRENT_DATE - INTERVAL FLOOR(RAND() * 14) DAY;

-- Date and time
SELECT CURRENT_TIMESTAMP - INTERVAL FLOOR(RAND() * 14 * 24 * 60 *60) SECOND;

Demo

UPDATE mytable
SET col = CURRENT_DATE - INTERVAL FLOOR(RAND() * 14) DAY

This sets col to a date between current date - 13 days and current date; both inclusive, total 14 days.