来自同一ID的多个表的MySQL sum列

Question

I have 18 table in mysql.

All of tables have a column Result (ex a.result, b.result etc..) I need to select the result of 18 table and sum together for all of the id.

d.id 1 = a.result + b.result + c.result (of id 1 in all of the table)

Thanks

Answer 1

Use UNION ALL to get all value from all 18 tables. Then use SUM function.

Query

SELECT SUM(t.result) FROM(
    SELECT result FROM table_1
    UNION ALL
    SELECT result FROM table_2
    UNION ALL
    ...........................
    ...........................
    SELECT result FROM table_18
)t;

If you want the result column value for specific id's from the table. Then, use WHERE .

Answer 2

It's not pretty, but something like this would work

SELECT a.result + b.result + c.result -- (All the way to r.result...)
FROM TableA a
INNER JOIN TableB b
  ON a.ID = b.ID
INNER JOIN TableC c
  ON b.ID = c.ID
-- (All the way to TableR ...)

You might want to consider using OUTER JOINS unless you're absolutely certain that the ID will always exist in all tables.