SQL将多行中的单元格合并为一个单元格

Question

与此处的问题类似： http://forums.asp.net/t/1580379.aspx/1 我正在尝试将公共单元格合并到一个逗号分隔的单元格中，但是要跨内部连接。

我的SQL是：

SELECT DISTINCT tb_Order.OrderNumber, tb_Order.OrderId, 
  tb_Order.orderDate, tb_Order.OrderTotal, 
  tb_OrderStatus.OrderStatus, tb_Order.GroupOrderId, 
  tb_Venue.Title AS Venue
FROM tb_Order INNER JOIN tb_OrderItem ON tb_Order.OrderId = tb_OrderItem.OrderId 
  INNER JOIN tb_Show ON tb_OrderItem.ShowId = tb_Show.showId 
  INNER JOIN tb_OrderStatus ON tb_Order.OrderStatusId = tb_OrderStatus.OrderStatusID 
  INNER JOIN tb_Venue ON tb_Show.VenueId = tb_Venue.id
WHERE (tb_Order.OrderId = 705)

我需要[地点]以逗号分隔，如：

"Interactive Seating Chart Advanced, Interactive Seating Chart Mode Multi-Click"

Answer 1

执行此操作的一种方法是使用行处理顺序的副作用来迭代填充变量，就像这样。这样做的缺点是它不能在简单的查询环境中工作，并且它不是最有效的解决方案。

    DECLARE @venues varchar(max)
      SET @venues = '' 

    SELECT @venues = 
      CASE WHEN @venues = '' THEN v.Title 
      ELSE @venues + ',' + v.Title END
    FROM tb_Venue v 

    SELECT @venues

第二种方法是使用STUFF和SQL Server XML扩展，如下所示：

        SELECT DISTINCT v.Title,
        (STUFF(
        (SELECT ',' + v2.Title
         FROM tb_Venue v2
        -- uncomment this line if you are going 
        -- to aggregate only by something in the outer query
        -- WHERE v2.GroupKey = v.GroupKey  
         ORDER BY v2.Title
         FOR XML PATH(''), TYPE, ROOT
        ).value('root[1]','varchar(max)'),1,1,'')) as Aggregation
        FROM tb_Venue v

基于CLR的解决方案通常是此用例中性能最高的解决方案，其中之一被描述为here以及其他一些不太理想的解决方案......

你的问题不是植根于设定逻辑的问题，所以没有一个干净的SQL解决方案......

Answer 2

如果您具有SQL Server 2017（14.x）和更高版本，则可以使用STRING_AGG函数。

SELECT tb_Order.OrderNumber, tb_Order.OrderId, 
  tb_Order.orderDate, tb_Order.OrderTotal, 
  tb_OrderStatus.OrderStatus, tb_Order.GroupOrderId, 
  STRING_AGG(tb_Venue.Title, ',') AS Venue
FROM tb_Order INNER JOIN tb_OrderItem ON tb_Order.OrderId = tb_OrderItem.OrderId 
  INNER JOIN tb_Show ON tb_OrderItem.ShowId = tb_Show.showId 
  INNER JOIN tb_OrderStatus ON tb_Order.OrderStatusId = tb_OrderStatus.OrderStatusID 
  INNER JOIN tb_Venue ON tb_Show.VenueId = tb_Venue.id
WHERE (tb_Order.OrderId = 705)
GROUP BY tb_Order.OrderNumber, tb_Order.OrderId, 
  tb_Order.orderDate, tb_Order.OrderTotal, 
  tb_OrderStatus.OrderStatus, tb_Order.GroupOrderId