I have a DB table which has columns named with few more other columns
ColorA
ColorB
Status
The data in this DB look like this.
ColorA ColorB Status
--------- --------- ---------
GREEN NULL YES
GREEN NULL YES
RED GREEN NO
RED GREEN YES
The result what I want is something like this depending on Status='YES'
Color Count
GREEN 3
RED 1
I have also defined table which hold all the color.
How to construct the SQL query for this which will result in the output as mentioned earlier? I have a query but I am using LEFT Join and then doing an UNION which is not giving proper result.
This should work:
SELECT a.color,
Count(a.color) AS Count
FROM (SELECT colora AS color
FROM table1
WHERE status = 'YES'
AND colora IS NOT NULL
UNION ALL
SELECT colorb
FROM table1
WHERE status = 'YES'
AND colorb IS NOT NULL) a
GROUP BY a.color
Result
| COLOR | COUNT | ----------------- | GREEN | 3 | | RED | 1 |
From the example you have given you want to know the count of each ColorA or ColorB record
SELECT Color, SUM(Total) AS Count
FROM (
SELECT ColorA as Color, SUM(CASE WHEN Status = 'Yes' THEN 1 ELSE 0 END) AS Total
Group By ColorA
UNION
SELECT ColorB as Color, SUM(CASE WHEN Status = 'Yes' THEN 1 ELSE 0 END) AS Total
Group By ColorB
) U
GROUP BY Color
This works in SQL Server, MySQL and PostgreSQL ( SQLFiddle demo ):
SELECT color, sum(cnt) AS count FROM (
SELECT colorA AS color, count(*) AS cnt
FROM mytable
WHERE status = 'YES'
GROUP BY colorA
UNION ALL
SELECT colorB AS color, count(*) AS cnt
FROM mytable
WHERE status = 'YES'
GROUP BY colorB
) AS x
WHERE color IS NOT NULL
GROUP BY color
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