Finding Top N

Question :- How to find Top N on different database engines ?
Solution :-

Teradata SQL  :-

select top 10 COL1, SUM(MEASURE)  from TABLE
group by 1
order by 2 desc


SQL Server :-

select top 10 COL1, SUM(MEASURE)  from TABLE
group by COL1
order by 2 desc


As you can see in the above examples that SQLs for teradata and SQL Server are similar. However Oracle engine does not accept TOP function therefore we will be using ROWNUM function, instead. You can also use Rank function in Oracle but i like to use rownum function, which is easier than rank. 

Oracle :-


SELECT  JOB_TITLE, SAL FROM
(select  JOB_Title, SUM(MAX_SALARY) SAL from JOBS
group by  Job_title
order by 2 desc ) A
WHERE ROWNUM <=10;