如何在 SQL Server 2014 中将一个字段的结果拆分为两个单独的字段

Question

我正在尝试生成一份报告，为我提供每小时、每条车道、每个方向的交通量。

目前我得到的结果：

|TransDate    |Hour  |Lane| Direction| Count|
---------------------------------------------
|2017-09-05   |1:00  |  1 |     NB   |  18  |
---------------------------------------------
|2017-09-05   |1:00  |  1 |     SB   |  12  |
---------------------------------------------
|2017-09-05   |1:00  |  2 |     NB   |  42  |
---------------------------------------------
|2017-09-05   |1:00  |  2 |     SB   |  31  |
---------------------------------------------
|2017-09-05   |1:00  |  3 |     NB   |   7  |
---------------------------------------------
|2017-09-05   |1:00  |  3 |     SB   |   8  |
---------------------------------------------

我希望得到的结果：

|TransDate    |Hour  |Lane|  NB  |  SB |
----------------------------------------
|2017-09-05   |1:00  |  1 |    18|  12 |
----------------------------------------
|2017-09-05   |1:00  |  2 |    42|  31 |
----------------------------------------
|2017-09-05   |1:00  |  3 |     7|   8 |
----------------------------------------

到目前为止，我的方法是联合两组代码。一组用于 NB 方向，另一组用于 SB 方向。

到目前为止我的代码：

SELECT  CAST(TransDT as DATE) as 'TransDate' 
       ,CAST(DATEPART(Hour, TransDT) as varchar) + ':00' as 'Hour' 
       ,LaneID
       ,Direction
       ,COUNT(*) as 'NB_Count'

FROM Traffic_analysis

WHERE cast(TransDT as date) = DATEADD (DAY, -1 , cast(SYSDATETIME() as date))
  AND Direction = 'NB'

GROUP BY CAST(TransDT as DATE), DATEPART(Hour, TransDT), LaneID, Direction
ORDER BY CAST(TransDT as DATE), DATEPART(Hour, TransDT), LaneID, Direction

这显然不是正确的方法，因为它不起作用。

我的方法应该是什么才能像第二个那样得到每个方向的计数 table？

Answer 1

您可以如下使用数据透视表：

Select * from 
( Select transdate, [hour], lane, direction, [count] from #transdata ) a
pivot (max([count]) for Direction in ([NB],[SB])) p

输出如下：

+------------+------------------+------+----+----+
| transdate  |       hour       | lane | NB | SB |
+------------+------------------+------+----+----+
| 2017-09-05 | 01:00:00.0000000 |    1 | 18 | 12 |
| 2017-09-05 | 01:00:00.0000000 |    2 | 42 | 31 |
| 2017-09-05 | 01:00:00.0000000 |    3 |  7 |  8 |
+------------+------------------+------+----+----+

如果您有方向的动态列表，您可以使用如下动态查询：

Declare @cols1 varchar(max)
Declare @query nvarchar(max)

Select @cols1 = stuff((select Distinct ','+QuoteName(Direction) from #transdata  for xml path('')),1,1,'')

Select @query = '   Select * from 
    ( Select transdate, [hour], lane, direction, [count] from #transdata ) a
    pivot (max([count]) for Direction in (' + @cols1 + ')) p '

Exec sp_executeSql @query

如何在 SQL Server 2014 中将一个字段的结果拆分为两个单独的字段

How to split results from one field into two separate fields in SQL Server 2014

sql-server

union-all