NULL строка исчезает только на PDO

Question

В поисках оптимизации запросов SQL для ускорения загрузки страницы за 20 секунд.Мы должны уменьшить количество запросов, которые мы имеем.Тезисы - это текущие запросы:

                SELECT
                    P.[Starting Date] as current_promo
                FROM [Sales Price] P
                WHERE P.[Item No_] = :id
                  AND P.[Ending Date] >= getdate()
                  AND P.[Starting Date] <= getdate()
              ORDER BY P.[Starting Date] ASC;

                SELECT
                    P.[Starting Date] as current_promo
                FROM [Purchase Line Discount] P
                WHERE P.[Item No_] = :id
                  AND (P.[Line Discount_] > 0 OR P.[Line Discount_2] > 0)
                  AND (P.[Ending Date] >= getdate() OR P.[Ending Date] = '1753-01-01 00:00:00.000')
                  AND (P.[Starting Date] <= getdate() OR P.[Starting Date] = '1753-01-01 00:00:00.000')
              ORDER BY P.[Starting Date] ASC;

                SELECT
                    P.[Lot Quantity] as lot,
                    P.[Free Quantity] as free
                FROM [Purchase Price] P
                WHERE P.[Item No_] = :id
                  AND (P.[Ending Date] >= getdate() OR P.[Ending Date] = '1753-01-01 00:00:00.000')
                  AND (P.[Starting Date] <= getdate() OR P.[Starting Date] = '1753-01-01 00:00:00.000')
              ORDER BY P.[Ending Date] ASC;

                SELECT
                    P.[Starting Date] as next_promo
                FROM [Purchase Price] P
                WHERE P.[Item No_] = :id
                  AND P.[Minimum Quantity] = 1
                  AND P.[Ending Date] > P.[Starting Date]
                  AND P.[Starting Date] > getdate()
              ORDER BY P.[Starting Date] ASC;

Нам нужен только первый результат каждого запроса.Хорошо, я могу сделать TOP 1, никаких проблем с этим.Но мне все еще нужно объединить эти 4 запроса.Вот один из моих проектов:

SELECT
       sales_promo,
       purchase_promo,
       lot, free,
       next_promo
FROM
     (
       SELECT TOP 1 P.[Starting Date] as sales_promo
       FROM [Purchase Line Discount] P
       WHERE P.[Item No_] = :id
         AND (P.[Line Discount _] > 0 OR P.[Line Discount _ 2] > 0)
         AND (P.[Ending Date] >= getdate() OR P.[Ending Date] = '1753-01-01 00:00:00.000')
         AND (P.[Starting Date] <= getdate() OR P.[Starting Date] = '1753-01-01 00:00:00.000')
       ORDER BY P.[Starting Date] ASC
       ) salesPromo FULL OUTER JOIN
     (
       SELECT TOP 1 P.[Starting Date] as purchase_promo
       FROM [Purchase Line Discount] P
       WHERE P.[Item No_] = :id
         AND (P.[Line Discount _] > 0 OR P.[Line Discount _ 2] > 0)
                 AND (P.[Ending Date] >= getdate() OR P.[Ending Date] = '1753-01-01 00:00:00.000')
         AND (P.[Starting Date] <= getdate() OR P.[Starting Date] = '1753-01-01 00:00:00.000')
       ORDER BY P.[Starting Date] ASC
     ) purchasePromo ON 1=1 FULL OUTER JOIN
     (
       SELECT TOP 1 P.[Lot Quantity] as lot, P.[Free Quantity] as free
       FROM [Purchase Price] P
       WHERE P.[Item No_] = :id
         AND (P.[Ending Date] >= getdate() OR P.[Ending Date] = '1753-01-01 00:00:00.000')
         AND (P.[Starting Date] <= getdate() OR P.[Starting Date] = '1753-01-01 00:00:00.000')
       ORDER BY P.[Ending Date] ASC
     ) lotandfee ON 1=1 FULL OUTER JOIN
     (
       SELECT TOP 1 P.[Starting Date] as next_promo
       FROM [Purchase Price] P
       WHERE P.[Item No_] = :id
         AND P.[Minimum Quantity] = 1
         AND P.[Ending Date] > P.[Starting Date]
         AND P.[Starting Date] > getdate()
       ORDER BY P.[Starting Date] ASC
     ) nextPromo ON 1=1

Отлично, это работает!

Вопрос :

По некоторым подзапросам у меня есть0 результатов.Когда я делаю этот запрос непосредственно в базе данных, у меня нет проблем, null, когда у меня нет результата для подзапроса и результата для второго подзапроса.Но когда я делаю это с PDO, всякий раз, когда у меня есть подзапрос с 0 результатом, я заканчиваю тем, что вся строка исчезает!

Вот еще один черновик, дающий тот же результат:

SELECT
       sales_promo
       purchase_promo,
       lot, free,
       next_promo
FROM
     (
       SELECT q.* FROM (SELECT NULL) AS d (dummy) LEFT JOIN (
         SELECT TOP 1 P.[Starting Date] as sales_promo
         FROM [Purchase Line Discount] P
         WHERE P.[Item No_] = :id
           AND (P.[Line Discount _] > 0 OR P.[Line Discount _ 2] > 0)
           AND (P.[Ending Date] >= getdate() OR P.[Ending Date] = '1753-01-01 00:00:00.000')
           AND (P.[Starting Date] <= getdate() OR P.[Starting Date] = '1753-01-01 00:00:00.000')
         ORDER BY P.[Starting Date] ASC
       ) AS q ON 1=1
       ) salesPromo,
     (
       SELECT q.* FROM (SELECT NULL) AS d (dummy) LEFT JOIN (
       SELECT TOP 1 P.[Starting Date] as purchase_promo
       FROM [Purchase Line Discount] P
       WHERE P.[Item No_] = :id
         AND (P.[Line Discount _] > 0 OR P.[Line Discount _ 2] > 0)
                 AND (P.[Ending Date] >= getdate() OR P.[Ending Date] = '1753-01-01 00:00:00.000')
         AND (P.[Starting Date] <= getdate() OR P.[Starting Date] = '1753-01-01 00:00:00.000')
       ORDER BY P.[Starting Date] ASC
       ) AS q ON 1=1
     ) purchasePromo,
     (
       SELECT q.* FROM (SELECT NULL) AS d (dummy) LEFT JOIN (
       SELECT TOP 1 P.[Lot Quantity] as lot, P.[Free Quantity] as free
       FROM [Purchase Price] P
       WHERE P.[Item No_] = :id
         AND (P.[Ending Date] >= getdate() OR P.[Ending Date] = '1753-01-01 00:00:00.000')
         AND (P.[Starting Date] <= getdate() OR P.[Starting Date] = '1753-01-01 00:00:00.000')
       ORDER BY P.[Ending Date] ASC
       ) AS q ON 1=1
     ) lotandfee,
     (
       SELECT q.* FROM (SELECT NULL) AS d (dummy) LEFT JOIN (
       SELECT TOP 1 P.[Starting Date] as next_promo
       FROM [Purchase Price] P
       WHERE P.[Item No_] = :id
         AND P.[Minimum Quantity] = 1
         AND P.[Ending Date] > P.[Starting Date]
         AND P.[Starting Date] > getdate()
       ORDER BY P.[Starting Date] ASC
       ) AS q ON 1=1
     ) nextPromo