Somme multiples agrégats de plusieurs tables sous

Question

Dites par exemple que j'ai les tableaux suivants:

| TableA 
+-------------------------------------------------------------+ 
| FIELD  | TYPE | NULL | KEY | DEFAULT | Extra   | 
+-------------------------------------------------------------+ 
| TableA_ID | Int  | NO | PK | NULL | Auto Increment | 
| Name  | Varchar | No |  | NULL |    | 
+-------------------------------------------------------------+ 

| TableB 
+-------------------------------------------------------------+ 
| FIELD  | TYPE | NULL | KEY | DEFAULT | Extra   | 
+-------------------------------------------------------------+ 
| TableB_ID | Int  | NO | PK | NULL | Auto Increment | 
| TableA_ID | Int  | No | FK | NULL |    | 
| Qty  | Decimal | No |  | NULL |    | 
+-------------------------------------------------------------+ 

| TableC 
+-------------------------------------------------------------+ 
| FIELD  | TYPE | NULL | KEY | DEFAULT | Extra   | 
+-------------------------------------------------------------+ 
| TableC_ID | Int  | NO | PK | NULL | Auto Increment | 
| TableA_ID | Int  | No | FK | NULL |    | 
| Qty  | Decimal | No |  | NULL |    | 
+-------------------------------------------------------------+ 

avec les lignes suivantes:

| Table A 
+-------------------------+ 
| TableA_ID | Name  | 
+-------------------------+ 
| 1   | "Record AA" | 
| 2   | "Record AB" | 
| 3   | "Record AC" | 
| 4   | "Record AD" | 
| 5   | "Record AE" | 
| 6   | "Record AF" | 
+-------------------------+ 

| TableB 
+-----------------------------+ 
| TableB_ID | TableA_ID | Qty | 
+-----------------------------+ 
| 1   | 1   | 5 | 
| 2   | 1   | 5 | 
| 3   | 2   | 7.5 | 
| 4   | 2   | 8 | 
| 5   | 2   | 11 | 
| 6   | 3   | 3 | 
| 7   | 4   | 5 | 
| 8   | 5   | 9 | 
| 9   | 5   | 13 | 
| 10  | 5   | 79 | 
+-----------------------------+ 

| TableC 
+------------------------------+ 
| TableC_ID | TableA_ID | Qty | 
+------------------------------+ 
| 1   | 1   | 7 | 
| 2   | 1   | 7 | 
| 3   | 2   | 2.25 | 
| 4   | 2   | 6 | 
| 5   | 2   | 13 | 
| 6   | 3   | 4 | 
| 7   | 4   | 19 | 
| 8   | 5   | 2 | 
| 9   | 6   | 19.5 | 
| 10  | 6   | 51 | 
+------------------------------+ 

J'ai commencé avec la requête suivante:

SELECT Name, 
    ISNULL(SUM(TableB.QTY),0.0), 
    ISNULL(SUM(TableC.QTY),0.0) 
FROM TableA 
    LEFT OUTER JOIN TableB ON TableA.TableA_ID = TableB.TableA_ID 
    LEFT OUTER JOIN TableC ON TableA.Table_ID = TableC.TableA_ID 
GROUP BY Name 

Le problème avec cette requête est qu'elle me donne des sommations incorrectes. Je passe ensuite à des sous-requêtes telles que ci-dessous:

SELECT Name, 
    ISNULL([SubTable1],0.0) TableB_TotalQty, 
    ISNULL([SubTable2],0.0) TableC_TotalQty 
FROM TableA 
    LEFT OUTER JOIN 
    (
     SELECT TableA_ID, SUM(Qty) [TotalQty] 
     FROM TableB 
     GROUP BY TableA_ID 
    ) [SubTable1] ON TableA.TableA_ID = [SubTable1].TableA_ID 
    LEFT OUTER JOIN 
    (
     SELECT TableA_ID, SUM(Qty) [TotalQty] 
     FROM TableC 
     GROUP BY TableA_ID 
    ) [SubTable2] ON TableA.TableA_ID = [SubTable2].TableA_ID 

Maintenant il d'autres façons de retourner les informations correctes autres que l'utilisation de sous-requêtes?

Answer 1

SELECT TA.Name, SumB = isnull(TB.SumB,0), SumC = isnull(TC.SumC,0) 
FROM TableA TA 
outer apply 
     (select SumB = sum(Qty) 
      from TableB 
      where TableA_ID = TA.TableA_ID) TB 
outer apply 
     (select SumC = sum(Qty) 
      from TableC 
      where TableA_ID = TA.TableA_ID) TC 

Answer 2

Il s'agit en réalité de deux requêtes distinctes pour chaque colonne. J'aime la solution @ DimaSUN qui utilise OUTER APPLY. Pour les anciennes versions de SQL Server (< 2005), combinant deux requêtes distinctes pour chaque colonne devrait également fonctionner:

select name, SumB, SumC from 
    (select a.tableA_ID, a.name, isnull(sum(b.qty),0) as [SumB] 
     from tableA a left join tableB b 
      on a.tableA_ID = b.tableA_ID 
     group by a.tableA_ID, a.name) q1 
    inner join 
    (select a.tableA_ID, isnull(sum(c.qty),0) as [SumC] 
     from tableA a left join tableC c 
      on a.tableA_ID = c.tableA_ID 
     group by a.tableA_ID) q2 
    on q1.tableA_ID = q2.tableA_ID 
    order by name; 

Une autre alternative, en utilisant Common Table Expressions (> = SQL 2005):

with CTE_TB as (
       select a.tableA_ID, a.name, isnull(sum(b.qty),0) as [SumB] 
        from tableA a left join tableB b 
        on a.tableA_ID = b.tableA_ID 
        group by a.tableA_ID, a.name), 
    CTE_TC as (select a.tableA_ID, isnull(sum(c.qty),0) as [SumC] 
        from tableA a left join tableC c 
        on a.tableA_ID = c.tableA_ID 
        group by a.tableA_ID) 
select name, SumB, SumC from CTE_TB a inner join CTE_TC b on a.tableA_ID=b.tableA_ID 
     order by name;