你如何在SQL Server中的Bit数据类型上进行PIVOT？

Question

这可能是一个非常简单的问题.我想要做的就是将列放入一个数据类型有点的行.

SUM,MIN,MAX不适用于位.COUNT有效,但我真的不想数.我只想将所有的东西从列移到行中,就像我拿了一把剪刀,切割信息并移动-90度.

Answer 1

解决方案是将位数据类型转换为聚合函数中接受的数据类型.例如,

SELECT MAX(CAST(BitColumn AS TINYINT))

将BitColumn值转换为tinyint数据类型.如果BitColumn包含至少一个值1,则该语句返回1; 否则,它返回0(除非所有值都为null).

假设如下:

CREATE TABLE MyTable (ID INT, Name VARCHAR(10), BitColumn BIT);

INSERT INTO MyTable VALUES (1, 'Name 1', 1);
INSERT INTO MyTable VALUES (1, 'Name 2', 0);
INSERT INTO MyTable VALUES (1, 'Name 3', 1);
INSERT INTO MyTable VALUES (2, 'Name 1', 1);
INSERT INTO MyTable VALUES (2, 'Name 2', 1);
INSERT INTO MyTable VALUES (2, 'Name 3', 1);
INSERT INTO MyTable VALUES (3, 'Name 1', 0);
INSERT INTO MyTable VALUES (3, 'Name 2', 0);
INSERT INTO MyTable VALUES (3, 'Name 3', 0);

您可以使用以下查询来转动此数据

SELECT ID,
    CAST(MAX(CASE Name WHEN 'Name 1' THEN CAST(BitColumn AS TINYINT) ELSE NULL END) AS BIT) AS [Name 1],
    CAST(MAX(CASE Name WHEN 'Name 2' THEN CAST(BitColumn AS TINYINT) ELSE NULL END) AS BIT) AS [Name 2],
    CAST(MAX(CASE Name WHEN 'Name 3' THEN CAST(BitColumn AS TINYINT) ELSE NULL END) AS BIT) AS [Name 3]
FROM MyTable
GROUP BY ID
ORDER BY ID

在这种情况下,最大BitColumn值从tinyint转换回bitint.这不是必需的.

结果是

ID  Name 1  Name 2  Name 3
--------------------------
1   1       0       1
2   1       1       1
3   0       0       0

对于SQL Server 2005及更高版本,备用查询使用PIVOT运算符

SELECT ID, [Name 1], [Name 2], [Name 3]
FROM
    (
    SELECT ID, Name, CAST(BitColumn AS TINYINT) AS BitColumn
    FROM MyTable
    ) as SourceTable
PIVOT
(
MAX(BitColumn) FOR Name in ([Name 1], [Name 2], [Name 3])
) AS PivotTable