回答編集履歴
2
修正
answer
CHANGED
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@@ -13,5 +13,5 @@
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13
13
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left join tableB as B1
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14
14
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on A.商品ID = B1.販売ID
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15
15
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left join tableB as B2
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16
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-
on A.商品ID = B2.在庫ID and
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16
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+
on A.商品ID = B2.在庫ID and B2.販売ID is Null
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17
17
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```
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1
追記
answer
CHANGED
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@@ -5,4 +5,13 @@
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5
5
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from tableA as A
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6
6
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left join tableB as B
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7
7
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on A.商品ID = coalesce(B.販売ID, B.在庫ID)
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8
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+
```
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9
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+
上記は前回の回答の別バージョンなので、上記で遅い遅い場合は以下を試してみて下さい。
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10
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+
```SQL
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11
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+
select 商品ID, coalesce(B1.品目, B2.品目) as 品目
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12
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+
from tableA as A
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13
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+
left join tableB as B1
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14
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+
on A.商品ID = B1.販売ID
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15
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+
left join tableB as B2
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16
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+
on A.商品ID = B2.在庫ID and B.販売ID is Null
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8
17
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```
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