回答編集履歴
4
SQL修正
answer
CHANGED
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@@ -19,7 +19,7 @@
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19
19
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20
20
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```SQL
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21
21
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SELECT user_id
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22
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-
FROM Table1
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22
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+
FROM Table1 AS a
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23
23
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WHERE item_id=1 AND
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24
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-
not exists (select user_id from table1 b where a.user_id = b.user_id AND item_id = 2);
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24
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+
not exists (select user_id from table1 AS b where a.user_id = b.user_id AND item_id = 2);
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25
25
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```
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3
さらに回答追加
answer
CHANGED
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@@ -14,3 +14,12 @@
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14
14
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FROM Table1
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15
15
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WHERE item_id=1 AND user_id Not In (select user_id from table1 where item_id = 2);
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16
16
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```
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17
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+
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18
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+
not exists を使うなら、
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19
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+
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20
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+
```SQL
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21
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+
SELECT user_id
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22
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+
FROM Table1
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23
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+
WHERE item_id=1 AND
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24
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+
not exists (select user_id from table1 b where a.user_id = b.user_id AND item_id = 2);
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25
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+
```
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2
回答追加
answer
CHANGED
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@@ -5,4 +5,12 @@
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5
5
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FROM Table1 AS a LEFT JOIN (select user_id From Table1 where item_id = 2) AS b
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6
6
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ON a.user_id = b.user_id
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7
7
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WHERE a.item_id=1 AND b.user_id Is Null;
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8
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-
```
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8
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+
```
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9
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+
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10
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+
IN演算子を使ってもよさそう。
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11
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+
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12
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+
```SQL
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13
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+
SELECT user_id
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14
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+
FROM Table1
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15
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+
WHERE item_id=1 AND user_id Not In (select user_id from table1 where item_id = 2);
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16
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+
```
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1
SQLコード修正
answer
CHANGED
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@@ -1,7 +1,7 @@
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1
1
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自己結合を使えばどうかな。
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2
2
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3
3
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```SQL
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4
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-
SELECT a.user_id
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4
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+
SELECT a.user_id
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5
5
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FROM Table1 AS a LEFT JOIN (select user_id From Table1 where item_id = 2) AS b
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6
6
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ON a.user_id = b.user_id
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7
7
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WHERE a.item_id=1 AND b.user_id Is Null;
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