What’s the difference between RANK() and DENSE_RANK() functions? How to find out nth salary in the following emptbl table? DEPTNO EMPNAME SAL —————————— 10 rrr 10000.00 11 nnn 20000.00 11 mmm 5000.00 12 kkk 30000.00 10 fff 40000.00 10 ddd 40000.00 10 bbb 50000.00 10 ccc 50000.00 If in the table data having nulls, what … Read more
Suppose I have pandas DataFrame like this: df = pd.DataFrame({‘id’:[1,1,1,2,2,2,2,3,4],’value’:[1,2,3,1,2,3,4,1,1]}) which looks like: id value 0 1 1 1 1 2 2 1 3 3 2 1 4 2 2 5 2 3 6 2 4 7 3 1 8 4 1 I want to get a new DataFrame with top 2 records for each … Read more
Can someone please explain what the partition by keyword does and give a simple example of it in action, as well as why one would want to use it? I have a SQL query written by someone else and I’m trying to figure out what it does. An example of partition by: SELECT empno, deptno, … Read more
I’ve been using GROUP BY for all types of aggregate queries over the years. Recently, I’ve been reverse-engineering some code that uses PARTITION BY to perform aggregations. In reading through all the documentation I can find about PARTITION BY, it sounds a lot like GROUP BY, maybe with a little extra functionality added in? Are … Read more
