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[程序员] 咨询个 SQL 数据去重的问题

发表于
目前有个流水表,大几千万的数据,可以简化如下:
会员号( member_id), 流水日期( trans_date)

有个需求,需要找出指定日期段内的会员数量(去重)
这个日期段时灵活的,可能时本月,本周,最近 7 天,最近 30 天

有什么方法能优化
1. 没办法根据日期段做汇总结果的统计表,因为日期段没有任何规律
2. 数据库为 mysql,目前用的 sum(distinct member_id) where trans_date between

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