回答編集履歴
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sample
test
CHANGED
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@@ -1,3 +1,47 @@
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そういう場合は都道府県名を羅列したテーブルを用意して
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3
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INNER JOINすればいいでしょう
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4
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# sample
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- 元データ
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10
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11
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```SQL
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create table pref(pid int unique,pname varchar(10));
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insert into pref values(1,'北海道'),(2,'東京都'),(3,'神奈川県'),(4,'大阪府');
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create table user(uid int unique,uname varchar(10),address varchar(100));
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insert into user values(1001,'佐藤','東京都新宿区ほげほげ'),(2,'鈴木','東京都渋谷区ほげほげ'),(3,'吉田','品川区ほげほげ'),(4,'田中','神奈川県横浜市ほげほげ');
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```
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- 集計
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```SQL
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select pname,count(*) as cnt
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from pref as t1
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inner join user as t2 on t2.address regexp concat('^',t1.pname)
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group by pname;
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```
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- 更新
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38
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```SQL
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update pref as t1,user as t2
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set t2.address=substr(t2.address,char_length(t1.pname)+1)
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44
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45
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where t2.address regexp concat('^',t1.pname);
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46
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47
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```
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