SQL 服务器 : get size of longest value in column and include column name in that total

Question

我有以下查询返回它在该列中找到的最长单词的数量:

SELECT 
    MAX(LEN(id)) AS id, 
    MAX(LEN(linkToTbl2)) AS linkToTbl2, 
    MAX(LEN(description)) AS description, 
    MAX(LEN(number)) AS number, 
    MAX(LEN(line)) AS line, 
    MAX(LEN(network)) AS network, 
    MAX(LEN(type)) AS type, 
    MAX(LEN(IPhase)) AS IPhase, 
    MAX(LEN(environment)) AS environment, 
    MAX(LEN(sType)) AS sType, 
    MAX(LEN(bDescription)) AS bDescription
FROM 
    bLine

但是，如果所述列小于该列的标题，则在计算最大值时不会将其考虑在内。

示例(我想要做什么):

|id | linkToTbl2 | description             |
+---+------------+-------------------------+
|14 |hi          |This is just a demo.     |
|16 |baa         |Another description here.|

在示例查询中看起来像这样:

|id |linkToTbl2 |description |
+---+-----------+------------+
|2  |10         |25          |

现在这是我的 SSRS 报告中目前的样子:

|id |lin|description              |
|   |kTo|                         |
|   |tbl|                         |
|   |2  |                         |
|---|---|-------------------------|
|14 |hi |This is just a demo.     |
|16 |baa|Another description here.|

这在查询中看起来像这样:

|id |linkToTbl2 |description |
|---|-----------|------------|
|2  |3          |25          |

请注意 linkToTbl2 字段是如何压缩的，因为该列中的最长值为 3 (baa)。 linkToTbl2 将是 10 (linkToTbl2)，因此它应该是 10 而不是 3。

我怎样才能将列名添加到查询中以将其也计算在内？

Answer 1

您可以使用 UNPIVOT 和 PIVOT

DECLARE @MyTable TABLE (id INT,  linkToTbl2 VARCHAR(100),  description  VARCHAR(100))
INSERT INTO @MyTable VALUES
(14,'hi','This is just a demo.'),
(16,'baa','Another description here.')


SELECT * FROM 
    ( SELECT 
        Col,  
        MAX(CASE WHEN LEN(Val) > LEN(Col) THEN LEN(Val) ELSE LEN(Col) END) LEN_OF_COL  
      FROM 
        ( SELECT 
                CONVERT(VARCHAR(MAX),[Id]) [Id], 
                CONVERT(VARCHAR(MAX),[linkToTbl2]) [linkToTbl2], 
                CONVERT(VARCHAR(MAX),[description]) [description] 
            FROM @MyTable ) SRC
        UNPIVOT (Val FOR Col IN( [Id], [linkToTbl2], [description] ) ) UNPVT
    GROUP BY Col ) T 
PIVOT( MAX(LEN_OF_COL) FOR Col IN ( [Id], [linkToTbl2], [description] ) ) PVT

结果:

Id          linkToTbl2  description
----------- ----------- -----------
2           10          25