如何在MySQL中选择具有相应ID的最大值

Question

SELECT 
    id
  , insId
  , MAX(avgRating) as avgRating 
FROM reviews 
WHERE status='1' 
GROUP BY insId

this query returns all reviews grouped by insId but id is not corresponding to this.

Answer 1

You need to use a self INNER JOIN to get the results you need.

SELECT
   reviews.id
 , reviews_max.insId
 , reviews_max.maxAvgRating
FROM (

  SELECT 
     insId
   , MAX(avgRating) AS maxAvgRating
  FROM
   reviews
  WHERE
   status = '1'
  GROUP BY
   insId
) AS reviews_max
INNER JOIN 
 reviews
ON
   reviews.insId = reviews_max.insId 
 AND
   reviews.avgRating = reviews_max.maxAvgRating

Answer 2

Try this:

SELECT 
    id
  , insId
  , MAX(avgRating) as avgRating 
FROM reviews 
WHERE status='1' 
GROUP BY id

Answer 3

You can try this out:

SELECT id, 
insId, 
MAX(avgRating) as avgRating 
FROM reviews 
WHERE status='1' 
GROUP BY id, insId