回答編集履歴
1
文法修正
test
CHANGED
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@@ -4,18 +4,16 @@
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4
4
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5
5
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```SQL
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6
6
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7
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-
SELECT
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7
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+
SELECT t1.post_id
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8
8
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9
9
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FROM table t1
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10
10
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11
11
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LEFT OUTER JOIN table t2 ON t1.post_id = t2.post_id
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12
12
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13
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-
WHERE t1.category_id = 3 AND t2.category_id = 4
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13
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+
WHERE t1.category_id = 3 AND t2.category_id = 4;
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14
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-
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15
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-
OR t1.category_id = 4 AND t2.category_id = 3;
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16
14
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17
15
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```
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18
16
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19
17
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20
18
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21
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-
DISTINCT
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19
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+
同じテーブル同士なのでOR文やDISTINCTは不要でしたね。
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