sqlitecountsql-updatecommon-table-expressionwindow-functions

How to rank rows based on two columns using SQLite


I have a table like this. I want to rank each row based on the date column so that the end result is the same rank if the two values of record_number and date are equal and different rank if the record_number and date is different. For example, the first two rows in the following table should have rank 1, while the third row should take rank 2 since the date is different but the record_number is the same.

record number date
4648 2015-06-17
4648 2015-06-17
4648 2015-06-18
4897 2015-12-03
6523 2020-01-09
6523 2022-04-01

I used this logic but all rows ranked as 1.

ALTER TABLE main_clinics
    ADD COLUMN visit_rank INTEGER;
UPDATE main_clinics
    SET
    visit_rank = (
        SELECT DENSE_RANK() OVER (PARTITION BY record_number ORDER BY date ASC)
        FROM main_clinics 
    );

Solution

  • If your version of SQLite is 3.33.0+ you can use a cte that returns all the ranks and with the UPDATE...FROM syntax join it to the table:

    WITH cte AS (
      SELECT *, DENSE_RANK() OVER (PARTITION BY record_number ORDER BY date) AS rnk
      FROM main_clinics
    )
    UPDATE main_clinics AS m
    SET visit_rank = c.rnk 
    FROM cte AS c
    WHERE c.record_number = m.record_number AND c.date = m.date;
    

    See the demo.

    For older versions of SQLite use a correlated subquery:

    UPDATE main_clinics AS m1
    SET visit_rank = (
      SELECT COUNT(DISTINCT date)
      FROM main_clinics AS m2
      WHERE m2.record_number = m1.record_number AND m2.date <= m1.date
    );
    

    See the demo.