回答編集履歴
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調整
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CHANGED
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@@ -1,2 +1,48 @@
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適切なインデックスを貼れば高速化は可能だと思います
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MySQLの例としてあげているSQLは明らかにおかしいので実行できません
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# テスト
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```SQL
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CREATE table table_a
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(
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ID int primary key auto_increment,
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YYYYMM CHAR(6) NOT NULL,
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CD1 CHAR(6) NOT NULL,
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CD2 CHAR(2) NOT NULL,
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CD3 CHAR(5) NOT NULL,
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CD4 CHAR(2) NOT NULL,
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CD5 CHAR(3) NOT NULL,
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MAX1 CHAR(5) NOT NULL ,
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MIN1 CHAR(5) NOT NULL,
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CD6 CHAR (3) NOT NULL,
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unique(YYYYMM, CD1, CD2),
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index(CD3,CD4,CD5,MAX1,MIN1,CD6)
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);
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insert into table_a(YYYYMM,CD1,CD2,CD3,CD4,CD5,MAX1,MIN1,CD6) values
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('202309','000001','01','30001','41','501','99001','90001','601'),
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('202309','000001','02','30001','41','501','99002','90001','601'),
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('202309','000001','03','30001','42','501','99003','90001','601'),
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('202309','000002','01','30001','41','501','99003','90001','601'),
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('202309','000002','02','30001','42','501','99002','90001','601');
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```
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explainで確認
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```SQL
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EXPLAIN SELECT
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CD3
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,CD4
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,CD5
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,MAX(MAX1)
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,MIN(MIN1)
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,COUNT(CD6)
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FROM table_a
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GROUP BY
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CD3
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41
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,CD4
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42
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,CD5
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```
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※結果
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45
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|id|select_type|table|partitions|type|possible_keys|key|key_len|ref|rows|filtered|Extra|
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46
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|--:|:--|:--|--:|:--|:--|:--|--:|:--|--:|--:|:--|
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47
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|1|SIMPLE|table_a|NULL|index|CD3|CD3|92|NULL|5|100.00|Using index|
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48
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