Question

我有查询：

select c.CustomerID 'Customer ID', c.CompanyName 'Company Name',
c.ContactName 'Contact Name', c.Address, c.City, 
c.StateOrRegion 'State Or Region', c.PostalCode 'Postal Code',
c.Country, c.Phone, c.Fax, o.OrderID 'Order ID', 
o.ShippedDate 'Shipped Date' 
from orders o 
left join Customers c 
on o.customerid = c.customerid
where o.shippeddate is not null
order by c.ContactTitle asc

结果，我有：

SELECT e.id_taxe
     , u.nm_user
     , dt_taxe
     , SUM(e.vl_taxe) as vl_taxe
FROM taxe as e 
  JOIN user as u 
    ON u.id_user = e.id_user 
WHERE id_enterprise = 86 
   AND dt_taxe BETWEEN '2017-01-01' AND '2017-03-31'
   AND lg_cancel = 0 
 GROUP 
    BY e.dt_taxe
     , e.id_user 
 ORDER 
    BY e.id_user
     , e.dt_taxe

如何连接行以获得结果：

id_taxe     nm_user   dt_taxe      vl_taxe
728         Maria     2017-01-01   17091.07048034668
727         Maria     2017-02-01   14091.07048034668
721         Maria     2017-03-01   1021.07048034668
731         Pedro     2017-01-01   16353.569854736328
732         Pedro     2017-02-01   6353.56231239

Answer 1

使用像PostgreSQL这样的数据库可以使用窗口函数来完成，但MySQL不支持窗口函数，所以你不能这样做

Answer 2

此类操作通常最好在应用程序层完成。您的结果集不是非常SQLish，因为排序非常很重要。

但是，您可以使用变量执行此操作：

SELECT (CASE WHEN rn = 1 THEN id_taxe END) as id_taxe,
       (CASE WHEN rn = 1 THEN nm_user END) as num_user,
       dt_taxe, vl_taxe
FROM (SELECT eu.*,
             (@rn := if(@u = e.id_user, @rn + 1,
                        if(@u := e.id_user, 1, 1)
                       )
             ) as rn
      FROM (SELECT e.id_taxe, u.nm_user, e.dt_taxe, SUM(e.vl_taxe) as vl_taxe
            FROM taxe e INNER JOIN
                 user u 
                 ON u.id_user = e.id_user 
            WHERE id_enterprise = 86 AND
                  dt_taxe BETWEEN '2017-01-01' AND '2017-03-31' AND
                  lg_cancel = 0
            GROUP BY e.dt_taxe, e.id_user
           ) eu CROSS JOIN
           (SELECT @i := -1, @rn := 0)
      ORDER BY id_user, dt_taxe
     ) eu;

具有相同用户的Concat行

2 个答案: