SQL - using alias in Group By

Question

Just curious about SQL syntax. So if I have

SELECT 
 itemName as ItemName,
 substring(itemName, 1,1) as FirstLetter,
 Count(itemName)
FROM table1
GROUP BY it         


        

Answer 1

I'm not answering why it is so, but only wanted to show a way around that limitation in SQL Server by using CROSS APPLY to create the alias. You then use it in the GROUP BY clause, like so:

SELECT 
 itemName as ItemName,
 FirstLetter,
 Count(itemName)
FROM table1
CROSS APPLY (SELECT substring(itemName, 1,1) as FirstLetter) Alias
GROUP BY itemName, FirstLetter