Sorting in order of days of birth

Such a sorting may be useful for getting the order of celebration of employees’ DOB.
The feature of this sorting is in ordering dates firstly by month, then by day of month without taking into account the year of birth at all.

Let’s consider the Battles table as an example, namely date column. It is evident that ordering by date does not required result due to the year (for example, October 20 follows after November 15):

select date
from Battles
order by date;

To solve the problem, two methods can be suggested (in SQL Server dialect).

1. Use of  CONVERT function

In so doing, we transform datetime value to the string representation in the format “mm-dd”

select convert(CHAR(5), date, 110) "mm-dd"
from Battles;

select date
from Battles
order by convert(CHAR(5),date,110);

2. Use of  MONTH and DAY functions

Here we use built-in functions which return date components - month (MONTH) and day (DAY) respectively. Let’s do sorting on these components:

select date
from Battles
order by MONTH(date), DAY(date);

As regards query performance, you can choose any method because optimizer produces identical execution plans for these.

Finally let’s give the last query in a more presentable form having included in it additionally a “hero of the festivities”:

select DAY(date) BD_day, DATENAME(mm, date) BD_month, name
from Battles
order by MONTH(date), DAY(date);