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Saturday, February 16, 2019

SQL Analytical Function: Teradata Vs. MS SQL syntax

A few years back, I posted about Teradata analytical function where I described how this works and why we need to use analytical function :  https://pauldhip.blogspot.com/2014/12/analytical-function-rownumber-with.html

However, this post includes SQL syntax for MS SQL and how it's different from Teradata.

The SQL Code I have written in Teradata in my earlier post to find latest version of the data by using below:
select INDUST_CODE,INDUSTRY_NAME
from INDUSTRY
QUALIFY
row_number() Over (partition by INDUST_CODE order by ACTIVATE_DATE desc)=1

Do you think, the above syntax will work in MS SQL? Not really!! MS SQL doesn't have QUALIFY function. You need to write the syntax a little different way and  a few extra lines required to achieve same results.

Let's translate the above syntax for MS SQL:

SELECT INDUST_CODE, INDUSTRY_NAME, RANKRESULT
FROM(
SELECT  INDUST_CODE, INDUSTRY_NAME ,
RANK() OVER (PARTITION BY INDUST_CODE ORDER BY ACTIVATE_DATE DESC) AS RANKRESULT  
 FROM INDUSTRY
) TT
WHERE TT.RANKRESULT=1 

As you see, for MS SQL we had to use sub query and RANK function to achieve the same result we got in Teradata.