Есть ли способ повысить производительность запроса, который использует несколько подзапросов в предложении select

Question

У меня есть запрос, который выбирает данные из двух таблиц, TABLE_1 и TABLE_2. Две таблицы связаны с id. Каждая строка в TABLE_1 может иметь ровно 4 строки в TABLE_2. Клиенту требуется представление, которое возвращает все данные из TABLE_1 и все данные из TABLE_2, но данные из TABLE_2 должны отображаться в виде столбцов в одной строке с. Например:

Вот запрос, который я использовал:

Select ID, NAME, LASTNAME,
(SELECT HomeType from #TABLE_2 where id = t1.ID order by ID OFFSET 0 ROW FETCH NEXT 1 ROW ONLY) as Row1Column1,
(SELECT HomeCost from #TABLE_2 where id = t1.ID order by ID OFFSET 0 ROW FETCH NEXT 1 ROW ONLY) as Row1Column2,
(SELECT HomeType from #TABLE_2 where id = t1.ID order by ID OFFSET 1 ROW FETCH NEXT 1 ROW ONLY) as Row2Column1,
(SELECT HomeCost from #TABLE_2 where id = t1.ID order by ID OFFSET 1 ROW FETCH NEXT 1 ROW ONLY) as Row2Column2,
(SELECT HomeType from #TABLE_2 where id = t1.ID order by ID OFFSET 2 ROW FETCH NEXT 1 ROW ONLY) as Row2Column1,
(SELECT HomeCost from #TABLE_2 where id = t1.ID order by ID OFFSET 2 ROW FETCH NEXT 1 ROW ONLY) as Row2Column2,
(SELECT HomeType from #TABLE_2 where id = t1.ID order by ID OFFSET 3 ROW FETCH NEXT 1 ROW ONLY) as Row2Column1,
(SELECT HomeCost from #TABLE_2 where id = t1.ID order by ID OFFSET 3 ROW FETCH NEXT 1 ROW ONLY) as Row2Column2 from #TABLE_1 as t1 

Пример моих данных:

CREATE TABLE #TABLE_1(ID int, NAME varchar(100), LASTNAME varchar(100))
CREATE TABLE #TABLE_2(ID int,HomeType varchar(100), HomeCost varchar(100) )



Insert into #TABLE_1 (ID, NAME, LASTNAME) VALUES (1, 'JOHN', 'SNOW')
Insert into #TABLE_2 (ID, HomeType, HomeCost) VALUES (1, 'Type1', 'Cost1')
 Insert into #TABLE_2 (ID, HomeType, HomeCost) VALUES (1, 'Type2', 'Cost2')
 Insert into #TABLE_2 (ID, HomeType, HomeCost) VALUES (1, 'Type3', 'Cost3')
 Insert into #TABLE_2 (ID, HomeType, HomeCost) VALUES (1, 'Type4', 'Cost4')

Я хочу такие результаты, но для 50000 строк это медленный

ID| NAME| ROW1COLUMN1 | ROW1COLUMN2 | ROW2COLUMN1 | ROW2COLUMN2 | ROW3COLUMN1 | ROW3COLUMN2 | ROW4COLUMN1 | ROW4COLUMN2
-------------------------
 1|JOHN | Type1       | Cost1       | Type2       | Cost2       | Type3     | Cost3         | Type4       | Cost4

Answer 1

Я не проверял этот запрос, но он должен работать. Не забудьте сделать индексы для идентификаторов, полей HomeType. Если поле «HomeType» является динамическим, вам необходимо добавить дополнительное поле «pos». Поле 'pos' должно быть уникальным для строк в TABLE_2 с одинаковыми идентификаторами.

SELECT t.ID, t.NAME, t.LASTNAME, t1.HomeType AS Row1Column1, t1.HomeCost AS Row1Column2, t2.HomeType AS Row2Column1, t2.HomeCost AS Row2Column2, t3.HomeType AS Row3Column1, t3.HomeCost AS Row3Column2, t4.HomeType AS Row4Column1, t4.HomeCost AS Row4Column2
FROM TABLE_1 t
JOIN TABLE_2 t1 ON t.ID = t1.ID AND t1.HomeType = 'Type1'
JOIN TABLE_2 t2 ON t.ID = t2.ID AND t2.HomeType = 'Type2'
JOIN TABLE_2 t3 ON t.ID = t3.ID AND t3.HomeType = 'Type3'
JOIN TABLE_2 t4 ON t.ID = t4.ID AND t4.HomeType = 'Type4'

Answer 2

Вы можете использовать PIVOT

WITH T2 AS (
    SELECT 
        ID, 
        HomeTypeRN = 'A' + CAST( ROW_NUMBER() OVER (PARTITION BY ID ORDER BY HomeType) AS VARCHAR),
        HomeType, 
        HomeCostRN = 'B' + CAST(ROW_NUMBER() OVER (PARTITION BY ID ORDER BY HomeType) AS VARCHAR), 
        HomeCost
    FROM #TABLE_2
)
SELECT 
    T1.ID, T1.Name, T1.LastName, [A1], [B1], [A2], [B2], [A3], [B3], [A4], [B4]
FROM #TABLE_1 T1
LEFT JOIN
(
    SELECT ID, 
    MAX(A1) AS A1, MAX(B1) AS B1, 
    MAX(A2) AS A2, MAX(B2) AS B2, 
    MAX(A3) AS A3, MAX(B3) AS B3, 
    MAX(A4) AS A4, MAX(B4) AS B4 
    FROM T2 
    PIVOT(
        MAX(HomeType) FOR HomeTypeRN IN ([A1],[A2],[A3],[A4])
    ) P1
    PIVOT(
        MAX(HomeCost) FOR HomeCostRN IN ([B1],[B2],[B3],[B4])
    ) P2
    GROUP BY ID
) P  ON P.ID = T1.ID

Answer 3

Если у вас четыре одинаковых типа, вы можете использовать условное агрегирование следующим образом:

select t1.id, t1.name, t1.lastname,
       max(case when t2.type = 'type1' then hometype end) as hometype_1,
       max(case when t2.type = 'type1' then homecost end) as homecost_1,
       max(case when t2.type = 'type2' then hometype end) as hometype_2,
       max(case when t2.type = 'type2' then homecost end) as homecost_2,
       max(case when t2.type = 'type3' then hometype end) as hometype_3,
       max(case when t2.type = 'type3' then homecost end) as homecost_3,
       max(case when t2.type = 'type4' then hometype end) as hometype_4,
       max(case when t2.type = 'type4' then homecost end) as homecost_4
from table1 t1 left join
     t2
     on t1.id = t2.id
group by t1.id, t1.name, t1.lastname;