How to display mySQL rows even if there are not SUM results? - mysql

Question

I am trying to display a report from mySQL. Here is my current query:
SELECT *,
Sum(CASE
WHEN alerts_data_status = 'goal' THEN 1
ELSE 0
END) AS goal,
Sum(CASE
WHEN alerts_data_status = 'delivered' THEN 1
ELSE 0
END) AS delivered,
Sum(CASE
WHEN alerts_data_status = 'closed' THEN 1
ELSE 0
END) AS closed
FROM alerts_data
WHERE alerts_data.company_id = 1
GROUP BY alerts_data.alerts_data_id
the thing is that if a alerts_data.id has 0 goal, 0 delivered, 0 closed, it won't be shown in the results. The query shows only the alerts_data.id with at least 1 goal or 1 delivered or 1 closed.
How can I achieve this?
Example output
company ---- id --- goal --- delivered --- closed
1 ---- 32 --- 1 ------ 4 ----- 10
1 ---- 11 --- 0 ------ 1 ----- 1
Thank you

Answer 1

I think the issue that you are having is that there are no rows in the table for the company. Use an aggregation query with no GROUP BY:
SELECT 1 as company_id,
COALESCE(SUM(alerts_data_status = 'goal'), 0) AS goal,
COALESCE(SUM(alerts_data_status = 'delivered'), 0) AS delivered,
COALESCE(SUM(alerts_data_status = 'closed'), 0) AS closed
FROM alerts_data ad
WHERE ad.company_id = 1;
This no GROUP BY, this is guaranteed to return one row -- even if the WHERE clause filters out all rows. A GROUP BY returns one row per group, so if all rows are filtered out, then there are no groups and no rows in the result set.
If you wanted to support multiple company ids, you could use a LEFT JOIN:
SELECT company_id,
COALESCE(SUM(alerts_data_status = 'goal'), 0) AS goal,
COALESCE(SUM(alerts_data_status = 'delivered'), 0) AS delivered,
COALESCE(SUM(alerts_data_status = 'closed'), 0) AS closed
FROM (SELECT 1 as company_id UNION ALL
SELECT 2 as company_id
) c LEFT JOIN
alerts_data ad
USING (company_id)
GROUP BY company_id;
The LEFT JOIN guarantees that there are rows for each company, so each will be in the result set.
You can also phrase this as:
SELECT 1 as company_id,
COALESCE(SUM(alerts_data_status = 'goal'), 0) AS goal,
COALESCE(SUM(alerts_data_status = 'delivered'), 0) AS delivered,
COALESCE(SUM(alerts_data_status = 'closed'), 0) AS closed
FROM alerts_data ad
WHERE ad.company_id = 1;
This no GROUP BY, this is guaranteed to return one row -- even if the WHERE clause filters out all rows. A GROUP BY returns one row per group, so if all rows are filtered out, then there are no groups and no rows in the result set.
If you wanted to support multiple company ids, you could use a LEFT JOIN:
SELECT c.company_id,
COALESCE(SUM(ad.alerts_data_status = 'goal'), 0) AS goal,
COALESCE(SUM(ad.alerts_data_status = 'delivered'), 0) AS delivered,
COALESCE(SUM(ad.alerts_data_status = 'closed'), 0) AS closed
FROM companies c LEFT JOIN
alerts_data ad
on c.company_id = ad.company_id
WHERE c.company_id IN (1) -- or a longer list
GROUP BY c.company_id;

Answer 2

You need a LEFT JOIN of alerts_list to alerts_data:
SELECT t.alerts_id,
SUM(a.alerts_data_status = 'goal') AS goal,
SUM(a.alerts_data_status = 'delivered') AS delivered,
SUM(a.alerts_data_status = 'closed') AS closed
FROM alerts_list AS t LEFT JOIN alerts_data AS a
ON a.alerts_data_id = t.alerts_id AND a.company_id = t.company_id
WHERE t.company_id = 1
GROUP BY t.alerts_data_id