4/8/2023 0 Comments Navicat for mysql student![]() ![]() ![]() So the RANK() function will assign and return the ranks of every row within a partition or full set of the result table that is ordered. This example is provided just to understand the difference between RANK() and DENSE_RANK() and row_number() functions. And the row_number() function will simply display the row numbers without considering any tied values. Here all the rows are provided with rank values in a series order with no gaps, even though there are ties in the sales column. We can rewrite the query with DENSE RANK() to understand the ranking without gaps. The important point to be noted here is that, when partition by clause is used, the rank is reinitialized at every partition. But in the year 2011, there is a tie of value 150 between Carl and Esther which makes the ranks as ‘1’ for both, and the rank for Alan is ‘3’. Output can be explained as, for the year 2010, no ties in the sales column, and hence the ranks are in ascending order. So in the year 2010, the least sales done by Esther which is 100, then by Carl which is 140 and finally by Alan which is 150.Now sort the content with the number of sales by each employee.Partition the data according to year- so the data should be displayed sales by each employee from the year 2010, 2011, and 2015 together.Select and display employee, year, sales, and RANK() with a RANK column titled as sales_rank.Let us include the partition by clause also in the above query and see the result. Thus we saw the gaps in the RANK() function is due to the ties in the value column. Now, again rank ‘6’ repeats for two more times and thus ranks ‘7’ and ‘8’ are omitted due to tie in the sales column for values 200. So ranks ‘4’ and ‘5’ are omitted and rank ‘6’ is assigned to the 6th row. Also note that, after assigning rank ‘3’ thrice, the very next rank assigned is ‘6’ because, rows which could have the ranks as ‘4’ and ‘5’ already gets the rank of ‘3’, due to tie in the sales column. ![]() When there is a tie in the sales column, for example, Alan, Carl, and Esther have sales of 150 (though during different years), the same rank of ‘3’ is assigned to all the three rows. We can see that ranks are assigned with gaps. So first, data is sorted in ascending order of the number of sales, then the rank is assigned to each row and the data is displayed. Also, there is an ORDER BY clause which specifies to order the data in ascending order of sales column. The query says to display the column employee, year, sales, and RANK() with a RANK column titled as sales_rank. This makes the gaps or holes in the rankings. This function considers the same values in a column as ties and skips assigning the consecutive ranks instead assigns the same rank to the row with a tie. So as discussed, the RANK() function returns ranks of rows under a specific partition which is neatly ordered in ascending or descending order. Once arranged in an order, only then can we identify whether there are ties in the values. Ordering the results is mandatory to assign the ranks to rows. PARTITION BY – this part of the query will order the result set in ascending or descending order.RANK() over ( … ) rank_column_name – this part of the query will return the result of RANK() function and the output will hold the column as rank_column_name.RANK() is used in the SELECT query, to return the desired ranks of rows as output from the table which is considered. ![]()
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