mysql count 中使用case when 带条件及去重

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SELECT CASE (SELECT NOW() > '2019-02-12 16:48:00') WHEN 1 THEN '男' WHEN 2 THEN '女' ELSE '未知' END as ages

　　

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1	COUNT(CASE WHEN A.expire_time<{0} AND A.expire_time<>0 THEN A.expire_time END) AS disabled_total

　对部分列去重

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1	DISTINCT ucd.course_id,ucd.user_id and CASE WHEN ucd.kind=0 THEN ucd.kind END