令和元年/ 2019-12-15 18:04
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MYSQL/ifnull
select distinct email from xxx where ifnull(email,'') = '';
+-------+
| email |
+-------+
| NULL |
| |
+-------+
2 rows in set (0.13 sec)
// Thanks.
NULLを空文字に変換
http://d.hatena.ne.jp/saw_yo/20110824/1314152369
empty