sql - 报表的 SQL 查询

Question

我正在编写一份汇总报告，到目前为止我已经掌握了数据，但我不确定如何从这里开始。我使用 SQL，但我的技能有限

我在临时表中有以下内容

ID   Count  Action
2   23      Installed
2   12      Uninstalled
2   36      Unchanged
3   12      Installed
3   25      Unchanged
4   35      Installed
4   25      Unchanged

我想把它转换成这种格式

ID  Installed   Uninstalled Unchanged
2   23          12          36
3   12          0           36
4   35          0           25

我不知道去哪里，甚至不知道如何开始实现这一目标，也找不到任何东西可以指引我正确的方向（我确定它在某个地方）

任何帮助都会得到帮助

Answer 1

它被称为枢轴

这是关于它的文档

语法是

SELECT <non-pivoted column>,
    [first pivoted column] AS <column name>,
    [second pivoted column] AS <column name>,

    ...

    [last pivoted column] AS <column name>
FROM
    (<SELECT query that produces the data>)
    AS <alias for the source query>
PIVOT
( 
    <aggregation function>(<column being aggregated>)
FOR
[<column that contains the values that will become column headers>]
    IN ( [first pivoted column], [second pivoted column],
    ... [last pivoted column])

) AS <alias for the pivot table>

<optional ORDER BY clause>;

Answer 2

尝试这个：

SELECT
  ID, 
  MAX(CASE WHEN "Action" = 'Installed' THEN Count END) AS 'Installed',
  MAX(CASE WHEN "Action" = 'Uninstalled ' THEN Count END) AS 'Uninstalled',
  MAX(CASE WHEN "Action" = 'Unchanged' THEN Count END) AS 'Unchanged'
FROM Table
GROUP BY ID;

或者像这样使用 SQL ServerPIVOT表运算符：

SELECT *
FROM 
(
   SELECT * FROM table
)t
PIVOT
(
   MAX("Count") FOR "Action" IN([Installed], [Uninstalled], [Unchanged])
) p

两者的 SQL Fiddle 演示

但是，对于未知数量的Actions，您必须像这样动态选择它们：

DECLARE @cols AS NVARCHAR(MAX);
DECLARE @query AS NVARCHAR(MAX);

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(Action) 
                    from Table1
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'');

SET @query = 'SELECT ID,  ' + @cols + ' from 
             (
                SELECT * FROM Table1
             ) x
             PIVOT 
             (
                MAX(count)
                FOR action IN (' + @cols + ')
             ) p ';

EXECUTE(@query);

SQL Fiddle Demo(动态版)

Answer 3

枢轴很好，但有时很慢。不试一试。

SELECT ID
    , SUM(CASE WHEN [Action] = 'Installed' THEN [Count] ELSE 0 END) AS Installed
    , SUM(CASE WHEN [Action] = 'Uninstalled' THEN [Count] ELSE 0 END) AS Uninstalled
    , SUM(CASE WHEN [Action] = 'Unchanged' THEN [Count] ELSE 0 END) AS Unchanged
FROM <table>
GROUP BY ID