SQL to calculate number of values for each day based on a max value from previous date

Question

Aryan Kumar · Answer

Sure, here is the SQL to calculate the number of values for each day based on a max value from the previous date:
SQL
SELECT
  date,
  COUNT(*) AS num_values
FROM
  (
    SELECT
      date,
      MAX(value) AS mavalue
    FROM
      my_table
    GROUP BY
      date
  ) AS t
GROUP BY
  date
HAVING
  mavalue IS NOT NULL
ORDER BY
  date;
This query will first calculate the maximum value for each day in the my_table table. It will then group the rows by date and count the number of rows for each date. The
HAVING clause ensures that only days with a maximum value are included in the results. The
ORDER BY clause sorts the results by date.
The following is an example of the output of the query:
date | num_values
------- | --------
2023-01-01 | 10
2023-01-02 | 20
2023-01-03 | 30

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SQL to calculate number of values for each day based on a max value from previous date

Steilla Mitchel

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