Question

I have a table with some project data. One column contains “Completion %”. By default the value is set to 0. What is the best way to structure the mySQL query and write a code to get the following 3 values:

• total users (every row WHERE PROJECT = 5)
• participants (WHERE PROJECT = 5 AND completion != 0)
• average completion rate (average of the % of participants)

I don’t think I can do it all in a single query…

Thanks

Answer 1

SELECT project_id,
  COUNT(*) AS total_users,
  COUNT(IF(completion != 0, rowID, NULL)) AS participants,
  AVG(IF(completion != 0, completion, NULL)) AS average_completion_rate
FROM Projects
WHERE project_id = 5
GROUP BY project_id;

It would be helpful in the future if you run SHOW CREATE TABLE of your table and include it in your question.

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Re comment: So it sounds like your table is something like this:

CREATE TABLE Projects (
  rowID         INT PRIMARY KEY,
  project_id    INT,
  completion    TINYINT
);

I have edited my suggested query above to match.