Ranking counts using an SQL query - sql

Question

I am using DB Browser for SQLite. I have a table in the following format:
+-----------+-------------------------------------+
| search_id | search_town |
+-----------+-------------------------------------+
| 1 | town1,town3 |
| 2 | town2,town4,town5 |
| 3 | town3,town5 |
| 4 | town2,town5 |
| 5 | town2,town3,town4 |
+-----------+-------------------------------------+
I would like to do a COUNT on the number of times town1 through town5 has appeared under search_town, and then rank in descending order the towns based on their respective counts. So far I have the following query:
SELECT SUM(CASE WHEN search_location LIKE '%town01%' THEN 1 ELSE 0 END) AS town01,
SUM(CASE WHEN search_location LIKE '%town02%' THEN 1 ELSE 0 END) AS town02,
SUM(CASE WHEN search_location LIKE '%town03%' THEN 1 ELSE 0 END) AS town03,
SUM(CASE WHEN search_location LIKE '%town04%' THEN 1 ELSE 0 END) AS town04,
SUM(CASE WHEN search_location LIKE '%town05%' THEN 1 ELSE 0 END) AS town05
FROM searches
...but am unable to do an ORDER BY as the towns and their counts are output as columns instead of rows in this format
+-------+-------+-------+-------+-------+
| town1 | town2 | town3 | town4 | town5 |
+-------+-------+-------+-------+-------+
| 12 | 31 | 12 | 24 | 12 |
+-------+-------+-------+-------+-------+
Is there another approach to this? Appreciate any comments.

Answer 1

You are turning your output in a single row using CASE WHEN, to convert it into multiple rows, you can try like following.
;WITH cte
AS (SELECT *
FROM (VALUES ('Town1'),
('Town2'),
('Town3'),
('Town4'),
('Town5')) T(town))
SELECT Count(*) [Count],
C.town
FROM [TABLE_NAME] T
INNER JOIN cte C
ON T.search_location LIKE '%' + C.town + '%'
GROUP BY C.town
ORDER BY Count(*) DESC
Online DEMO
Another approach can be using UNION ALL.
SELECT *
FROM (SELECT Count(*) s,
'Town1' AS Col
FROM tablename
WHERE search_location LIKE '%town1%'
UNION ALL
SELECT Count(*) s,
'Town2' AS Col
FROM tablename
WHERE search_location LIKE '%town2%'
UNION ALL
SELECT Count(*) s,
'Town3' AS Col
FROM tablename
WHERE search_location LIKE '%town3%'
UNION ALL
SELECT Count(*) s,
'Town4' AS Col
FROM tablename
WHERE search_location LIKE '%town4%'
UNION ALL
SELECT Count(*) s,
'Town5' AS Col
FROM tablename
WHERE search_location LIKE '%town5%') t
ORDER BY s DESC

Answer 2

You can use a recursive common-table expression (CTE) to turn the comma-separated list into a set of rows. When the table is normalized, you can group by town and sort by descending count:
WITH rec(town, remain)
AS (
SELECT SUBSTR(search_town, 0, INSTR(search_town, ',')) -- Before ,
, SUBSTR(search_town, INSTR(search_town, ',')+1) || ',' -- After ,
FROM t1
UNION ALL
SELECT SUBSTR(remain, 0, INSTR(remain, ',')) -- Before ,
, SUBSTR(remain, INSTR(remain, ',')+1) -- After ,
FROM rec
WHERE LENGTH(remain) > 0
)
SELECT town
, COUNT(*)
FROM rec
GROUP BY
town
ORDER BY
COUNT(*) DESC
Idea from this blog post. Working example at sqliteonline.