SQL server full join query - sql

Question

I have a full join sql query and i am retrieving the data from the same table.the problem is i am getting the null value where i am expecting the column name.
Example:
I am having a table where there are two columns typeOfPost,dob.
DOB TypeOfPost
--------- --------------
20/11/1998 Manager
1/1/2000 Sales
13/6/1999 Manager
20/1/1987 Manager
1/11/1985 Sales
Now when I am writing a join query like
select DATENAME(month,dob) as Red,count(TypeOfPost)
from tablename
where TypeOfPost='Manager'
group by DATENAME(month,dob) as A
full join
select DATENAME(month,dob) as Green,count(TypeOfPost)
from tablename
where TypeOfPost='Sales'
group by DATENAME(month,dob) as B on B.Green = A.Red
Output-- Expected Output--
--------------------- ---------------------
Month Man Sal Month Man Sal
-------- ----- ------ -------- ----- ------
January 1 1 January 1 1
NULL 1 NULL June 1 NULL
November 1 1 November 1 1
Now here the problem rise, I want 'June' in the column Month instead of NULL value.
So is there any way to get that??
Help me out.
Thanks.

Answer 1

One option is to
use a CASE statement in a subselect
Determine for given record if it is a manager or sales
substitute with 1 or 0 accordingly
SELECT and GROUP from this subselect the final results.
SQL Statement
SELECT Month
, SUM(Man) AS Man
, SUM(Sal) AS Sal
FROM (
SELECT DATENAME(MONTH, DOB) AS Month
, CASE WHEN TypeOfPost = 'Manager' THEN 1 ELSE 0 END AS Man
, CASE WHEN TypeOfPost = 'Sales' THEN 1 ELSE 0 END AS Sal
FROM tableName
) g
GROUP BY
Month
or
SELECT Month
, SUM(Man)
, SUM(Sal)
FROM (
SELECT DATENAME(MONTH, DOB) AS Month
, COUNT(TypeOfPost) AS Man
, 0 AS Sal
FROM tableName
WHERE TypeOfPost = 'Manager'
GROUP BY
DATENAME(MONTH, DOB)
UNION ALL
SELECT DATENAME(MONTH, DOB) AS Month
, 0 AS Man
, COUNT(TypeOfPost) AS Sal
FROM tableName
WHERE TypeOfPost = 'Sales'
GROUP BY
DATENAME(MONTH, DOB)
) g
GROUP BY
Month