SQL Interview Questions and Answers Series | HackerRank | SYMMETRIC PAIRS | Advanced Join 

Other way can be like this too right select distinct f1.x , f1.y from functions f1 join functions f2 on f1.x=f2.y and f1.y=f2.x where f1.x1 ) order by f1.x;

General Context - We use the GROUP BY clause to categorize data before applying the HAVING clause. The GROUP BY clause groups rows together based on shared values in one or more columns. The HAVING clause then filters these groups based on a condition applied to aggregate functions (e.g., COUNT) in this case. Generally, HAVING allows filtering based on aggregate values, which aren't available until after the data is grouped. For instance, here you can't filter for symmetric pairs with a "COUNT > 1" until the rows are grouped and the count is calculated. So, we've used the GROUP BY just to segregate the pairs.

@@datasciencewithnish as a follow up, why didn't you used x1

Same doubt

Did you understand why it's happening? Could you please let me know?

okey actual problem is that when you use x1

@@coc3311 Yeah Got it ...Thank You for the explanation.