PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

Calculating Dates in MySQL
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An option that may not seem immediately obvious is using MySQL. MySQL provides
an extensive range of date manipulation functions that work for times outside the
reliable range of Unix timestamps.You need to connect to a MySQL server to run a
MySQL query, but you do not have to use data from the database.
The following query adds one day to the date February 28, 1700, and returns the
resulting date:
select adddate(‘1700-02-28’, interval 1 day)
The year 1700 is not a leap year, so the result is 1700-03-01.
You can find an extensive syntax for describing and modifying dates and times
described in the MySQL manual; it is located at http://www.mysql.com/doc/en/
Date_and_time_functions.html.
Unfortunately, there is not a simple way to get the number of years between two
dates, so the birthday example is still a little flaky.You can get a person’s age in days very
easily, and Listing 21.2 converts that age to years imprecisely.
Listing 21.2 mysql_calc_age.php—Using MySQL to Work Out a Person’s Age
Based on Birthdate