Question

So I have an example table called items with the following columns:

• item_id (int)
• person_id (int)
• item_name (varchar)
• item_type (varchar) – examples: ‘news’, ‘event’, ‘document’
• item_date (datetime)

…and a table person with the following columns: ‘person_id’, ‘person_name’.

I was hoping to display a list of the top 2 submitters (+ the COUNT() of items submitted) in a given time period for each item_type. Here’s basically what I was hoping the MySQL output would look like:

person_name  | item_type | item_count  Steve Jobs   | document  | 11 Bill Gates   | document  | 6 John Doe     | event     | 4 John Smith   | event     | 2 Bill Jones   | news      | 24 Bill Nye     | news      | 21 

How is this possible without making a separate query for each item_type? Thanks in advance!

Answer 1

SELECT  item_type, person_name, item_count FROM    (         SELECT  item_type, person_name, item_count,                 @r := IFNULL(@r, 0) + 1 AS rc,                 CASE WHEN @_item_type IS NULL OR @_item_type <> item_type THEN @r := 0 ELSE 1 END,                 @_item_type := item_type,         FROM    (                 SELECT  @r := 0,                         @_item_type := NULL                 ) vars,                 (                 SELECT  item_type, person_name, COUNT(*) AS item_count                 FROM    items                 GROUP BY                         item_type, person_name                 ORDER BY                         item_type, person_name, item_count DESC                 ) vo         ) voi WHERE   rc < 3