回答編集履歴
4
訂正
answer
CHANGED
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@@ -1,5 +1,5 @@
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1
1
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**C**を基準にするなら条件が逆。
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2
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-
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2
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+
それと演算の場所が違います。
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3
3
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```SQL
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4
4
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SELECT *
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5
5
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FROM posts c
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3
修正
answer
CHANGED
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@@ -4,5 +4,5 @@
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4
4
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SELECT *
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5
5
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FROM posts c
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6
6
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LEFT JOIN posts p
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7
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-
ON DATE_FORMAT(p.created_at, "%Y%m%d") = DATE_FORMAT(c.created_at
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7
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+
ON DATE_FORMAT(p.created_at, "%Y%m%d") = DATE_FORMAT(c.created_at - INTERVAL 1 YEAR, "%Y%m%d")
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8
8
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```
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2
修正
answer
CHANGED
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@@ -4,5 +4,5 @@
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4
4
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SELECT *
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5
5
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FROM posts c
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6
6
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LEFT JOIN posts p
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7
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-
ON DATE_FORMAT(p.created_at, "%Y%m%d") = DATE_FORMAT(c.created_at, "%Y%m%d")
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7
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+
ON DATE_FORMAT(p.created_at, "%Y%m%d") = DATE_FORMAT(c.created_at - INTERVAL 1 YEAR, "%Y%m%d")
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8
8
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```
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1
追記
answer
CHANGED
|
@@ -1,4 +1,5 @@
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|
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1
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-
Cを基準にするなら条件が逆
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1
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+
**C**を基準にするなら条件が逆。
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2
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+
ただ、逆にしなくても全件Nullにはならないと思いますが。
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2
3
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```SQL
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3
4
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SELECT *
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4
5
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FROM posts c
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