通過order_id分組並將id分配給mysql中的offer_id

Question

我有兩個表格，分別是X和表格Y.X有order_id，offer_id。一個order_id可以有多個offer_id。現在我想要插入數據到Y（id，offer_id），以這種方式爲每個不同的offer_id組合我想要一個id。例如。

表X：

order_id offer_id 
2581681  24 
2581681  23 
2581936  23 
2581936  24 
2582001  23 
2582001  24 
2595298  24 
2595298  14 
2596247  24 
2596247  14 
2596268  14 
2596268  24 
1911365  1 
1922052  1 
1922803  1 
1923501  1 
1924074  1 
1924963  1 

數據表Y應該是這樣的：

id  offer_id 
1   23 
1   24 
2   14 
2   24 
3   1 

Answer 1

如果你想要的任何數量的優惠，那麼問題就比較硬。這與您想要的接近：

select (@rn := @rn + 1) id, offers 
from (select group_concat(distinct x.offer_id order by x.offer_id) as offers 
     from tableX x 
     group by x.order_id 
    ) xx cross join 
    (select @rn := 0) var 
group by offers; 

這會將報價放在逗號分隔列表的單行中。如果你真的需要它們放在單獨的行，然後，我會建立在此：

select id, substring_index(substring_index(offers, ',', n.n), ',', -1) as offer 
from (select (@rn := @rn + 1) id, offers 
     from (select group_concat(distinct x.offer_id order by x.offer_id) as offers, 
        count(distinct x.offer_id) as numoffers 
      from tableX x 
      group by x.order_id 
      ) xx cross join 
      (select @rn := 0) var 
     group by offers 
    ) o join 
    (select 1 as n union all select 2 as n union all select 3 as n union all select 4 as n 
    ) n 
    on n.n <= numoffers; 

當然，n子查詢需要有至少提供了一個訂單的最大數量。