回答編集履歴
1
chousei
test
CHANGED
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@@ -51,3 +51,67 @@
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51
51
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and num=t1.num);
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```
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54
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# 検証
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58
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まずグルーピング処理
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61
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```SQL
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62
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select num,count(distinct name) as cnt from tbl
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64
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group by num;
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66
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67
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```
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68
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|num|cnt|
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|--:|--:|
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|1|1|
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|2|1|
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|3|2|
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|4|2|
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|5|2|
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|6|3|
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これを、cntが複数（>1）で絞り込む
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```SQL
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select num,count(distinct name) as cnt from tbl
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group by num
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having count(distinct name)>1
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```
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|num|cnt|
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|--:|--:|
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|3|2|
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|4|2|
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|5|2|
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|6|3|
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113
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ここまでがカッコ内の処理
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114
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115
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ここで抽出されるnumと、外側のテーブルnumを
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where existsを使うと絞込める
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