使用 SQL 服务器在 CTE 中自动生成列名

Question

我正在 CTE 中构建数据透视查询。我有一个 table Table_1:

Store      Week     xCount
-------    ----     ------
101        1        138
105        1        37
109        1        59
101        2        282
109        2        97
105        3        60
109        3        87

这是我用来转换的查询 Table_1:

with CTE as 
(
    select 
        *
    from 
        (select 
             store, week, xCount
         from 
             table_1) src
    pivot
        (sum(xcount)
             for week in ([1], [2], [3])
    ) piv;
)
Select * 
From CTE

这是我得到的结果：

| STORE |   1 |   2 |   3 |
+-------+-----+-----+-----+
|   101 | 138 | 282 | null|
|   105 |  37 | null|  60 |
|   109 |  59 |  97 |  87 |

结果还好，现在又多了一个WEEK。

我想开发一个带有数据透视查询的 CTE，它将自动生成不同的周并在此基础上创建一个列。

我做了一些研究，发现可以使用递归 CTE 来执行此操作。我是递归 CTE 的新手，所以请任何人帮助我解决这个问题。

我也尝试过动态数据透视查询，但 CTE 不允许动态查询。

请帮忙。

Answer 1

dynamic pivot doesn't work inside CTE

不，但 CTE 在动态查询中起作用：

{assuming you have declared the variables used below}
SELECT @Cols = {query to get the column names in a comma-separated string}

SET @sql='
with CTE as 
(
    select 
        *
    from 
        (select 
             store, week, xCount
         from 
             table_1) src
    pivot
        (sum(xcount)
             for week in ('+@Cols+')
    ) piv;
)
Select * 
From CTE
'

EXEC (@sql)

Can i use recursive CTE?

不，这不是递归 CTE 的合适用例。

Answer 2

/* Variable to hold unique Week to be used in PIVOT clause */
DECLARE @Weeks  NVARCHAR(MAX) = N''
/* Extract unique Week names with pivot formattings */
SELECT @Weeks  = @Weeks  + ', [' + COALESCE(week, '') + ']'
FROM (SELECT DISTINCT week FROM table_1) DT
/* Remove first comma and space */
SELECT @Weeks = LTRIM(STUFF(@Weeks , 1, 1, ''))


/* Variable to hold t-sql query */
DECLARE @CTEStatement NVARCHAR(MAX) = N''
/* Generate dynamic PIVOT query here */
SET @CTEStatement=N'
;WITH CTE as 
( SELECT *
    FROM 
        (SELECT
             store
            ,week
            ,xCount
         FROM 
             table_1) SRC
    PIVOT
        (SUM(xcount)
             FOR week in ('+ @Weeks +')
    ) PIV;
)
SELECT * 
FROM CTE
'

EXEC (@CTEStatement)

使用 SQL 服务器在 CTE 中自动生成列名

Automatically generate columns name in CTE using SQL Server

tsql

sql-server

common-table-expression