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select sum(coalesce(id,0)) from tbl1;
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> Date: Tue, 20 Jan 2009 10:17:07 +0900
> From: akiro@sibagaki.com
> Subject: [mysql 14716] sum´Ø¿ô¤Î¥Ð¡¼¥¸¥ç¥ó¤Ë¤è¤ëÆ°ºî¤Î°ã¤¤
> To: ml@mysql.gr.jp
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> create table tbl1(id int);
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> select sum(id) from tbl1;
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