What to use in place of union in above query i wrote or more optimize query then my given query without union and union all - sql

Question

I am counting the birthdays , sales , order in all 12 months from customers table in SQL server like these
In Customers table birth_date ,sale_date, order_date are columns of the table
select 1 as ranking,'Birthdays' as Type,[MONTH],TOTAL
from ( select DATENAME(month, birth_date) AS [MONTH],count(*) TOTAL
from customers
group by DATENAME(month, birth_date)
)x
union
select 2 as ranking,'sales' as Type,[MONTH],TOTAL
from ( select DATENAME(month, sale_date) AS [MONTH],count(*) TOTAL
from customers
group by DATENAME(month, sale_date)
)x
union
select 3 as ranking,'Orders' as Type,[MONTH],TOTAL
from ( select DATENAME(month, order_date) AS [MONTH],count(*) TOTAL
from customers
group by DATENAME(month, order_date)
)x
And the output is like these(just dummy data)
ranking
Type
MONTH
TOTAL
1
Birthdays
January
12
1
Birthdays
April
6
1
Birthdays
May
10
2
Sales
Febrary
8
2
Sales
April
14
2
Sales
May
10
3
Orders
June
4
3
Orders
July
3
3
Orders
October
6
3
Orders
December
17
I want to find count of these all these three types without using UNION and UNION ALL, means I want these data by single query statement (or more optimize version of these query)

Answer 1

Another approach is to create a CTE with all available ranking values ​​and use CROSS APPLY for it, as shown below.
WITH ranks(ranking) AS (
SELECT * FROM (VALUES (1), (2), (3)) v(r)
)
SELECT
r.ranking,
CASE WHEN r.ranking = 1 THEN 'Birthdays'
WHEN r.ranking = 2 THEN 'Sales'
WHEN r.ranking = 3 THEN 'Orders'
END AS Type,
DATENAME(month, CASE WHEN r.ranking = 1 THEN c.birth_date
WHEN r.ranking = 2 THEN c.sale_date
WHEN r.ranking = 3 THEN c.order_date
END) AS MONTH,
COUNT(*) AS TOTAL
FROM customers c
CROSS APPLY ranks r
GROUP BY r.ranking,
DATENAME(month, CASE WHEN r.ranking = 1 THEN c.birth_date
WHEN r.ranking = 2 THEN c.sale_date
WHEN r.ranking = 3 THEN c.order_date
END)
ORDER BY r.ranking, MONTH