Ranking Inside a Partition
Understand how to rank the rows inside the partition of window functions.
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In previous examples, we have witnessed the importance of accessing the first and last rows within a partition. Although the partition ordering already implies a definition of the first and last row, explicitly ranking rows inside a partition gives us more fine-grained control. This applies to peers resulting from ties between values concerning the partition order, in particular. Here, peers refer to rows that are equal in value subject to the partition order. To handle this case, MySQL offers three window functions that rank the rows within a partition, namely RANK(), DENSE_RANK(), and PERCENT_RANK().
Absolute ranks with gaps
The RANK() is a function without arguments that assigns each row its rank within the partition where peers receive the same rank. Groups of adjacent peers concerning the partition order do not receive consecutive ranks. That is, a group of