SQL Server: Select with dynamic column

Question

I have a stored procedure with the following piece. Now I would need the exact same procedure for several different scenarios where the only difference is that instead of "policy" I will refer to another column.

In order to avoid writing multiple stored procedures, is there a way I can use a variable input to define this specific column without having to make the whole procedure dynamic ?

INSERT INTO @temp
(       
            ranking,
            item,
            groupCount,
            groupName
)
SELECT      RANK() OVER(ORDER BY COUNT(*) desc, policy) [Rank],
            policy, 
            COUNT(*) AS groupCount,
            'currentMonth' AS groupName
FROM        Log_PE 
WHERE       CONVERT(DATE, dateEsc, 120) >= CONVERT(DATE, CONVERT(VARCHAR(6), GETDATE(), 112) + '01', 112)
GROUP BY    policy
ORDER BY    groupCount desc, policy

Many thanks for any help with this Tim.

Answer 1

Yes, you can use dynamic SQL to achieve what you desire. First, create a variable to hold the name of the column that will vary. Then, create another variable to hold the dynamically generated query. Finally, use sp_executesql to run this dynamic query. The code will look something like this:

declare @colname varchar(50) = ''

declare @query nvarchar(8000) = 'INSERT INTO @temp (ranking,item,groupCount,groupName)'
+ 'SELECT RANK() OVER(ORDER BY COUNT(*) desc,' + @colname + ') [Rank],' + @colname 
+ 'COUNT(*) AS groupCount, 'currentMonth' AS groupName FROM Log_PE'
+ 'WHERE CONVERT(DATE, dateEsc, 120) >= CONVERT(DATE, CONVERT(VARCHAR(6), GETDATE(),112)      
+  '01', 112)'
+ 'GROUP BY ' + @colname
+ ' ORDER BY groupCount desc, ' + @colname

execute sp_executesql @query