Brief discussion on Row_number () over () analysis function usage ____ static function in Oracle

Sort functions in Groups

Row_number () over (partition by col1 ORDER by col2) is grouped according to col1, sorted by col2 within the group, and the value of this function represents the sequential number of the internal sort in each group (a sequential unique within the group).

The difference between the rownum and the rownum is that the result set is first sorted by adding a fake rownum and then sorted, and the function is sorted before the line number is counted after the sort clause is included.

Row_number () is about the same as rownum, which is a bit more powerful (you can sort from 1 in each group).
Rank () is a jump sort, with two second names followed by fourth place (also within each group)
Dense_rank () is also a sequential sort, with two second names still followed by third. In contrast, there is no duplicate value for row_number.