Join two sql queries

Question

I have two SQL queries, where the first one is:

select Activity, SUM(Amount) as "Total Amount 2009"
from Activities, Incomes
where Activities.UnitName = ? AND
      Incomes.ActivityId = Activities.ActivityID
GROUP BY Activity
ORDER BY Activity;

and the second one is:

select Activity, SUM(Amount) as "Total Amount 2008"
from Activities, Incomes2008
where Activities.UnitName = ? AND
      Incomes2008.ActivityId = Activities.ActivityID
GROUP BY Activity
ORDER BY Activity;

(Dont mind the '?', they represent a parameter in birt). What i want to achieve is the following: I want an SQL query that returns the same as the first query, but with an additional (third) column which looks exactly like "Total Amount 2008" (from the 2nd query).

Answer 1

Try this:

select Activity, SUM(Incomes.Amount) as "Total Amount 2009", SUM(Incomes2008.Amount) 
as "Total Amount 2008" from
Activities, Incomes, Incomes2008
where Activities.UnitName = ?  AND
Incomes.ActivityId = Activities.ActivityID  AND
Incomes2008.ActivityId = Activities.ActivityID GROUP BY
Activity ORDER BY Activity;

Basically you have to JOIN Incomes2008 table with the output of your first query.

Answer 2

SELECT Activity, arat.Amount "Total Amount 2008", abull.Amount AS "Total Amount 2009"
FROM
  Activities a
LEFT OUTER JOIN
  (
  SELECT ActivityId, SUM(Amount) AS Amount
  FROM Incomes ibull
  GROUP BY
    ibull.ActivityId
  ) abull
ON abull.ActivityId = a.ActivityID
LEFT OUTER JOIN
  (
  SELECT ActivityId, SUM(Amount) AS Amount
  FROM Incomes2008 irat
  GROUP BY
    irat.ActivityId
  ) arat
ON arat.ActivityId = a.ActivityID
WHERE a.UnitName = ?
ORDER BY Activity

Answer 3

I would just use a Union

In your second query add the extra column name and add a '' in all the corresponding locations in the other queries

Example

//reverse order to get the column names
select top 10 personId, '' from Telephone//No Column name assigned 
Union 
select top 10 personId, loanId from loan

Answer 4

If you assume that values exist for all activities in both years then just do an inner join as follows

 select act.activity, t1.amount as "Total 2009", t2.amount as "Total 2008"
from Activities as act,
    (select activityid,  SUM(Amount) as amount
    from Activities, Incomes
    where Activities.UnitName = ? AND
          Incomes.ActivityId = Activities.ActivityID
    GROUP BY Activityid) as t1,
    (select activityid, SUM(Amount) as amount
    from Activities, Incomes2008
    where Activities.UnitName = ? AND
          Incomes2008.ActivityId = Activities.ActivityID
    GROUP BY Activityid) as t2
    WHERE t1.activityid= t2.activityid
    AND act.activityId = t1.activityId
    ORDER BY act.activity

If you can't assume this, then look at doing an outer join

Answer 5

perhaps not the most elegant way to solve this

select  Activity, 
     SUM(Amount) as "Total_Amount",
     2009 AS INCOME_YEAR
from    Activities, Incomes
where Activities.UnitName = ? AND
      Incomes.ActivityId = Activities.ActivityID
GROUP BY Activity
ORDER BY Activity;

UNION

select  Activity, 
     SUM(Amount) as "Total_Amount",
     2008 AS INCOME_YEAR
from Activities, Incomes2008
where Activities.UnitName = ? AND
      Incomes2008.ActivityId = Activities.ActivityID
GROUP BY Activity
ORDER BY Activity;

Answer 6

Some DBMSs support the FROM (SELECT ...) AS alias_name syntax.

Think of your two original queries as temporary tables. You can query them like so:

SELECT t1.Activity, t1."Total Amount 2009", t2."Total Amount 2008"
FROM (query1) as t1, (query2) as t2
WHERE t1.Activity = t2.Activity