SELECT id HAVING maximum count of id

问题

Have a products table with item_id and color_id. I'm trying to get the color_id with the most non-null instances.

This fails:

SELECT color_id 
  FROM products 
 WHERE item_id=1234 
 GROUP BY item_id 
HAVING MAX(COUNT(color_id))

with

Invalid use of group function

This

SELECT color_id, COUNT(color_id)
  FROM products 
 WHERE item_id=1234 
 GROUP BY item_id

Returns

color_id count
1, 323
2, 122
3, 554

I am looking for color_id 3, which has the most instances.

Is there a quick and easy way of getting what I want without 2 queries?

回答1:

SELECT color_id AS id, COUNT(color_id) AS count 
FROM products 
WHERE item_id = 1234 AND color_id IS NOT NULL 
GROUP BY color_id 
ORDER BY count DESC
LIMIT 1;

This will give you the color_id and the count on that color_id ordered by the count from greatest to least. I think this is what you want.

for your edit...

SELECT color_id, COUNT(*) FROM products WHERE color_id = 3;

回答2:

SELECT color_id
FROM
    (
        SELECT  color_id, COUNT(color_id) totalCount
        FROM    products 
        WHERE   item_id = 1234 
        GROUP   BY color_id 
    ) s
HAVING totalCount = MAX(totalCount)

UPDATE 1

SELECT  color_id, COUNT(color_id) totalCount
FROM    products 
WHERE   item_id = 1234 
GROUP   BY color_id 
HAVING  COUNT(color_id) =
(
  SELECT  COUNT(color_id) totalCount
  FROM    products 
  WHERE   item_id = 1234 
  GROUP   BY color_id 
  ORDER BY totalCount DESC
  LIMIT 1  
)

SQLFiddle Demo (having tie)

回答3:

SELECT 
  color_id, 
  COUNT(color_id) AS occurances
FROM so_test
GROUP BY color_id
ORDER BY occurances DESC
LIMIT 0, 1

Here is a sample fiddle with a basic table that shows it working: sql fiddle

来源：https://stackoverflow.com/questions/14249689/select-id-having-maximum-count-of-id

标签

mysql

sql

select

group-by

having-clause