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