Question

See the SQL query below, it count the total records that match with numbers and business tables.

SELECT N.mobile, B.name, count(*) as Total FROM records as R
 LEFT JOIN business as B ON B.id = R.business_id
 LEFT JOIN numbers as N ON N.id  = R.numbers_id 
group by N.mobile, B.name

However, there are remaining rows (N.mobile, B.name) that are not included in the result, how to include them and the Total would be 0?

Answer 1

Are you saying that there are business and numbers rows that don’t have an entry in records, but you want to include them in the count? Since MySQL doesn’t support a FULL OUTER JOIN use UNION to get the results you want:

SELECT N.mobile, B.name, count(*) as Total FROM records as R
LEFT JOIN business as B ON B.id = R.business_id
LEFT JOIN numbers as N ON N.id  = R.numbers_id 
GROUP BY N.mobile, B.name

UNION

SELECT N.mobile, NULL, 0
FROM numbers AS N
LEFT JOIN records as R ON N.id = R.numbers_id
WHERE r.numbers_id IS NULL

UNION

SELECT NULL, B.Name, 0
FROM business AS B
LEFT JOIN records as R ON B.id = R.business_id
WHERE r.business_id IS NULL