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MySQL query to group data into different ranges

I found a solution for this here, sql query that groups different items into buckets

It works well as long as there is data for all ranges. I want the query to return 0 if there is no data.

So if my table is:

item_name | price
i1        | 2
i2        | 22
i3        | 4
i4        | 26
i5        | 44
i6        | 6

I need output as:

range   | number of item
0 - 10  |  3
11 - 20 |  0
21 - 30 |  2
31 - 40 |  0
41 - 50 |  1

The following query does not display the result for counting 0 cases.

select
      case when price >= 0 and price <= 10    then "  0 - 10"
           when price > 10 and price <= 20   then " 10 - 20"
           when price > 20 and price <= 30   then " 20 - 30"
           when price > 30 and price <= 40  then " 30 - 40"
           when price > 40 and price <= 50  then " 40 - 50"
           else "over 50"
      end PriceRange,
      count(*) as TotalWithinRange
   from
      YourTable
   group by 1

Does anyone have a solution for this?

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3 answers


You need to build an inline table containing all price ranges. Then execute LEFT JOIN

with a derived table based on your query to get the expected result:

SELECT x.PriceRange, COALESCE(TotalWithinRange, 0) AS TotalWithinRange
FROM (
  SELECT "0 - 10" AS PriceRange 
  UNION SELECT "10 - 20"
  UNION SELECT "20 - 30"
  UNION SELECT "30 - 40"
  UNION SELECT "40 - 50"
  UNION SELECT "over 50" ) x
LEFT JOIN (  
   SELECT
      CASE when price >= 0 and price <= 10 then "0 - 10"
           when price > 10 and price <= 20 then "10 - 20"
           when price > 20 and price <= 30 then "20 - 30"
           when price > 30 and price <= 40 then "30 - 40"
           when price > 40 and price <= 50 then "40 - 50"
           else "over 50"
      END AS PriceRange,
      COUNT(*) as TotalWithinRange
   FROM YourTable
   GROUP BY 1 ) y ON x.PriceRange = y.PriceRange


Demo SQL Fiddle

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Group by TotalWithinRange

, so it will count each category



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This may not be the most efficient answer, but you can try separate instructions SUM(CASE)

for each group. For example:

SUM(CASE WHEN price >= 0 AND price <= 10 THEN 1 ELSE 0 END) AS "0-10"

Etc. This should print even categories with SUM 0.

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