mysql count how many times the same value appears across multiple colums - php

Question

during a group project we recent sent out a survey regarding the site we're building. I've put the data into a mysql database and i'm trying to figure out how to count how many times certain scores was given in each category
the table looks like this
+-----------------+--------------+-------------------+
| Design | Ease of use | Responsiveness |
+-----------------+--------------+-------------------+
| 5 | 5 | 5
| 4 | 4 | 4
| 3 | 3 | 3
| 2 | 2 | 2
| 1 | 1 | 1
| 5 | 4 | 2
| 5 | 4 | 4
| 3 | 3 | 3
| 1 | 2 | 2
| 1 | 2 | 2
I've found a query that works for one colum
SELECT Design, COUNT(*) AS num FROM table GROUP BY Design
I would then get
Design | num
-------------
5 | 3
4 | 1
3 | 2
2 | 1
1 | 3
If i were to try
SELECT Design, COUNT(*) AS num1, Ease of use, COUNT(*) as num2 FROM table
GROUP BY Design, Ease of use
The table gets totally messed up.
What I want is to get
Design | num1 | Ease of use | num2 | Responsiveness | num3
------------- --------------------------------------------------
5 | 3 | 5 | 1 | 5 | 1
4 | 1 | 4 | 3 | 4 | 2
3 | 2 | 3 | 2 | 3 | 2
2 | 1 | 2 | 3 | 2 | 4
1 | 3 | 1 | 1 | 1 | 1
Any help would be greatly appreciated

Answer 1

You can unpivot the values and then aggregate. In MySQL, that typically uses union all:
select val, count(*)
from ((select design as val from table) union all
(select ease_of_use from table) union all
(select responsiveness from table
) der
group by val
order by val desc;
For what you want to get, you can do:
select val, sum(design) as design, sum(ease_of_use) as ease_of_use,
sum(responsiveness) as responsiveness
from ((select design as val, 1 as design, 0 as ease_of_use, 0 as responsiveness from table) union all
(select ease_of_use, 0, 1, 0 from table) union all
(select responsiveness, 0, 0, 1 from table
) der
group by val
order by val desc;
I see no reason to repeat the value three times.

Answer 2

Use a synthesized table with the different values, and join this with subqueries that get the counts of each score.
SELECT nums.num AS Design, t1.count AS num1,
nums.num AS `Ease of Use`, t2.count AS num2,
nums.num AS Responsiveness, t3.count AS num3
FROM (SELECT 1 AS num UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) AS nums
LEFT JOIN (
SELECT Design, COUNT(*) AS count
FROM yourTable
GROUP BY Design) AS t1 ON t1.Design = nums.num
LEFT JOIN (
SELECT `Ease of Use`, COUNT(*) AS count
FROM yourTable
GROUP BY `Ease of Use`) AS t2 ON t2.`Ease of Use` = nums.num
LEFT JOIN (
SELECT Responsiveness, COUNT(*) AS count
FROM yourTable
GROUP BY Responsiveness) AS t3 ON t3.Responsiveness = nums.num
DEMO

Answer 3

Here are three ways:
select s.score,
(select count(*) from tbl where `Design` = s.score) as `Design`,
(select count(*) from tbl where `Ease of use` = s.score) as `Ease of use`,
(select count(*) from tbl where `Responsiveness` = s.score) as `Responsiveness`
from (
select Design as score from tbl
union select `Ease of use` from tbl
union select Responsiveness from tbl
) s
order by score desc
http://sqlfiddle.com/#!9/002303/2
select s.score,
(select count(*) from tbl where `Design` = s.score) as `Design`,
(select count(*) from tbl where `Ease of use` = s.score) as `Ease of use`,
(select count(*) from tbl where `Responsiveness` = s.score) as `Responsiveness`
from (select 1 as score union select 2 union select 3 union select 4 union select 5) s
order by score desc
http://sqlfiddle.com/#!9/002303/4
select s.score,
sum(`Design` = score) as `Design`,
sum(`Ease of use` = score) as `Ease of use`,
sum(`Responsiveness` = score) as `Responsiveness`
from (select 1 as score union select 2 union select 3 union select 4 union select 5) s
cross join tbl t
group by s.score
order by s.score desc
http://sqlfiddle.com/#!9/002303/5
They all return the same result:
| score | Design | Ease of use | Responsiveness |
|-------|--------|-------------|----------------|
| 5 | 3 | 1 | 1 |
| 4 | 1 | 3 | 2 |
| 3 | 2 | 2 | 2 |
| 2 | 1 | 3 | 4 |
| 1 | 3 | 1 | 1 |
As #futureweb wrote in the comment, I don't see a reason to repeat the score three times. Though you can if you want using aliases.
If you have millions of rows ;-) and no indexes you would want to get the result with only one table scan. This is possible with:
select
sum(`Design` = 1) as d1,
sum(`Design` = 2) as d2,
sum(`Design` = 3) as d3,
sum(`Design` = 4) as d4,
sum(`Design` = 5) as d5,
sum(`Ease of use` = 1) as e1,
sum(`Ease of use` = 2) as e2,
sum(`Ease of use` = 3) as e3,
sum(`Ease of use` = 4) as e4,
sum(`Ease of use` = 5) as e5,
sum(`Responsiveness` = 1) as r1,
sum(`Responsiveness` = 2) as r2,
sum(`Responsiveness` = 3) as r3,
sum(`Responsiveness` = 4) as r4,
sum(`Responsiveness` = 5) as r5
from tbl
This will return the data you need, but not in the form you'd like:
| d1 | d2 | d3 | d4 | d5 | e1 | e2 | e3 | e4 | e5 | r1 | r2 | r3 | r4 | r5 |
|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|
| 3 | 1 | 2 | 1 | 3 | 1 | 3 | 2 | 3 | 1 | 1 | 4 | 2 | 2 | 1 |
So you would need to post process it.