Is this query possible in sqlite? - sql

Question

I have a table like this:
ID A B C
0 x x
1 x
2 x x
3 x
I would like to obtain this with a query (SQLite syntax if possible)
A 3
B 2
C 1
I've been using CASE WHEN clause, like this
WITH solutions AS (SELECT
CASE
WHEN `B` = 'x' THEN 'A'
WHEN `B` = 'x' THEN 'B'
WHEN `C` = 'x' THEN 'C'
END AS 'Solution'
FROM use_cases)
SELECT solution, COUNT(*) AS 'Count'
FROM solutions
GROUP BY Solution ORDER BY COUNT(*) DESC
But it won't work in case a row present more than one column with 'x', as the WHEN evaluation will stop at the first case is found.

Answer 1

Use union all:
select col, count(*)
from (select 'A' as col from t where A = 'x' union all
select 'B' from t where B = 'x' union all
select 'C' from t where C = 'x'
) x
group by col
order by count(*) desc;

Answer 2

You need UNION ALL:
select 'A' col1, count(A = 'x') col2 from tablename
union all
select 'B', count(B = 'x') from tablename
union all
select 'C', count(C = 'x') from tablename
See the demo.
Or with a CTE to avoid multiple scans of the table:
with cte as (
select count(A = 'x') cola, count(B = 'x') colb, count(C = 'x') colc
from tablename
)
select 'A' col1, cola col2 from cte
union all
select 'B', colb from cte
union all
select 'C', colc from cte
See the demo.
Results:
| col1 | col2 |
| ---- | ---- |
| A | 3 |
| B | 2 |
| C | 1 |

Answer 3

If you specifically wanted to check for the X then you could take advantage of the fact that (at least in SQLite) TRUE is equivalent to 1 and FALSE to 0 so something simple like the following would work:
SELECT 'A', sum(A = 'x') from MyTable
UNION ALL
SELECT 'B', sum(B = 'x') from MyTable
UNION ALL
SELECT 'C', sum(C = 'x') from MyTable;
Another simple solution is to rely on the fact that count() only counts non-null values. So if the columns contain NULL in the places where it doesn't contain an X, then this simple SQL will work in SQLite:
SELECT 'A', count(A) from MyTable
UNION ALL
SELECT 'B', count(B) from MyTable
UNION ALL
SELECT 'C', count(C) from MyTable;
A slight variant of the above ... If the columns that don't contain X have something in them other than NULL … then just convert that to null. For example if the columns that don't contain an X happen to contain a space then the following would work:
SELECT 'A', count(nullif (A, ' ')) from MyTable
UNION ALL
SELECT 'B', count(nullif (B, ' ')) from MyTable
UNION ALL
SELECT 'C', count(nullif (C, ' ')) from MyTable;
Note: My proposed approaches will likely require multiple scans of the table but with proper indexing such a penalty could be mitigated. It is possible that CTE-based solutions may be more efficient but you would have to test both approaches to be sure. CTE-based solutions may involve the creation of temp tables (or temp result sets) from potentially multiple subqueries. All of which can make CTEs less efficient in certain circumstances … but YMMV.

Answer 4

Try this
Select val, cnt from ( SELECT 'A' as val,A,count(*) as cnt FROM TABLE
GROUP BY A
UNION
SELECT 'B' as val,B,count(*) as cnt FROM TABLE
Group by B
UNION
SELECT 'C' as val,C,count(*) as cnt FROM TABLE
Group by C))
Check below output
or if you want to exclude empty space count then
SELECT VAL,CNT FROM(SELECT 'A' AS VAL,A as col,COUNT(*) AS CNT FROM SAMPLEE GROUP BY A
UNION
SELECT 'B' AS VAL,B as col,COUNT(*) AS CNT FROM SAMPLEE GROUP BY B
UNION
SELECT 'C' AS VAL,C as col,COUNT(*) AS CNT FROM SAMPLEE GROUP BY C
) where col !=' ';