MySQL:Sum værdier i underforespørgsler

Nogle forslag:

• Deltag på seasons enkelt gang. En joinforbindelse får rækker fra den venstre tabel til at blive duplikeret, så de kan summeres to gange med sum samlet. Hvis du er i tvivl, så kør forespørgslen uden group by for et eksempel på en skole.
• Du skal relatere underforespørgslen til den ydre forespørgsel med noget som inner_schools.id = outer_schools.id
• Men så vidt jeg kan se, behøver du slet ikke en underforespørgsel

For eksempel:

SELECT  schools.*
,       sum(cashflows.amount) total_branding_cashflow
FROM    schools
JOIN    seasons
ON      seasons.school_id = schools.id 
        and seasons.year = 2010
JOIN    cashflows
ON      cashflows.season_id = seasons.id 
        and cashflow_group_id = 12
GROUP BY 
        schools.id 
HAVING  total_branding_cashflow BETWEEN 50000000 AND 100000000

For flere kategorier kan du bruge en sag:

SELECT  schools.*
,       sum(case when cashflow_group_id = 1 then cashflows.amount end) total1
,       sum(case when cashflow_group_id = 12 then cashflows.amount end) total12
FROM    schools
JOIN    seasons
ON      seasons.school_id = schools.id 
        and seasons.year = 2010
JOIN    cashflows
ON      cashflows.season_id = seasons.id 
GROUP BY 
        schools.id