MySql - Get Min, Max, and 3 random Rows

Question

I want a MySql query to get 5 rows which include min price row, max price row and other 3 random row.

Table:

ID  Product Price
1   data    2
2   data    20
3   data    55
4   data    24
5   data    2
6   data    15
7   data    10
8   data    33
9   data    3
10  data    30

Expected Result(with 3 random rows)

ID  Product Price
1   data    2
3   data    55
4   data    24
6   data    15
7   data    10

Any help would be greatly appreciated!

Answer 1

SELECT table.*
  FROM table
     , ( SELECT @minPrice := ( SELECT min(Price) FROM table ) minPrice
              , @minId    := ( SELECT id FROM table WHERE Price = @minPrice ORDER BY rand() LIMIT 1 )
              , @maxPrice := ( SELECT max(Price) FROM table ) maxPrice
              , @maxId    := ( SELECT id FROM table WHERE Price = @maxPrice ORDER BY rand() LIMIT 1 )
       ) tmp
  WHERE table.id in (@minId,@maxId)
UNION
(SELECT *
   FROM table
   WHERE Price not in (@minPrice,@maxPrice)
   ORDER BY rand()
   LIMIT 3
)

Answer 2

You can do this like ,

select * from table order by Price asc limit 0,1
union all
select * from table order by Price desc limit 0,1 
union all
select * from table order by RAND()  limit 0,3 

Answer 3

you can get it with UNION and sub-query:

(SELECT * FROM table ORDER BY Price ASC LIMIT 0 , 1 )
UNION ALL 
(SELECT * FROM table ORDER BY Price DESC limit 0,1 )
UNION ALL 
(SELECT * FROM table WHERE Price NOT IN ( SELECT CONCAT( MIN(  `Price` ) ,  ',', MAX(  `Price` ) ) AS MaxPrice FROM table ) ) ORDER BY RAND( ) LIMIT 0 , 3 ) 

Answer 4

SELECT x.*
  FROM my_table x 
  JOIN (SELECT MIN(price) a, MAX(price) b FROM my_table) y 
 ORDER 
    BY COALESCE(x.price NOT IN (a,b))
     , RAND() 
 LIMIT 5;

To address Keith's concerns... so, if we should always have 3, and either 1 or 5...

SELECT x.id
     , x.product
     , x.price
  FROM my_table x 
  JOIN (
        (SELECT id FROM my_table ORDER BY price, RAND() LIMIT 1)
        UNION
        (SELECT id FROM my_table ORDER BY price DESC, RAND() LIMIT 1)
       ) y
   GROUP
      BY x.id
       , x.product
       , x.price
 ORDER 
    BY MIN(COALESCE(x.id != y.id)) 
     , RAND()
 LIMIT 5;

...but this is starting to be a bit of a mouthful - it may be smarter to solve this in application code.

Answer 5

So ... get the min, get the max, get all the other records that are not min and max, sort by rand and return the first 3 that are not min and max.

Here is the SQL fiddle

-- get the first occurence of any item matching the products and prices returned
select min(top_bottom_and_3_random.id) id, top_bottom_and_3_random.product, top_bottom_and_3_random.price from (
    -- get the min and the max
    select distinct product, price from top_bottom_and_3_random where price in (
        select max( price) from top_bottom_and_3_random
        union select min( price ) from top_bottom_and_3_random
    ) union 
    select product, price from ( 
        -- get 3 random rows that are not max or min
        select rand() rand, product, price from (
            select product, price from top_bottom_and_3_random where price not in (
                select max( price) from top_bottom_and_3_random
                union select min( price ) from top_bottom_and_3_random
            ) group by product, price
        ) rand_product_price_group
         order by rand
         limit 3
    ) random_mix
) min_max_3_random
inner join top_bottom_and_3_random
on min_max_3_random.product = top_bottom_and_3_random.product
and min_max_3_random.price = top_bottom_and_3_random.price
group by top_bottom_and_3_random.product, top_bottom_and_3_random.price
order by id

-- example results
id  product price
1   data    2
3   data    55
4   data    24
7   data    10
10  data    30

Answer 6

You can take help of MySQL sub-query to get the desired result

select * from table WHERE Price = (SELECT MIN(Price ) FROM table)
union all
select * from table WHERE Price = (SELECT MAX(Price ) FROM table)
union all
select * from table order by RAND()  limit 0,3