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uj5u.com熱心網友回復：
可以用條件exists，也可以用關聯實作select count(1) from(
select distinct firs.buyer_id from table1 as firs--第一天
where exists(
select 1 from
table1 as sec --第二天
where DATEDIFF(DAY,firs,sec)=1
and firs.buyer_id=sec.buyer_id
and firs.item_id<>sec.item_id --第一天和第二天購買商品不同
and exists(
select 1 from
table1 as tree --第三天
where DATEDIFF(DAY,firs.buy_date,tree.buy_date)=2
and firs.buyer_id=tree.buyer_id
and firs.item_id<>tree.item_id --第一天和第三天購買商品不同
)) as a
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標籤：MySQL