SQL - 从表格数据创建汇总统计

Question

我有以下表

Manager-category StartDate Enddate 
A     1/1/2002  2/2/2007 
B     1/5/2005  4/5/2005 
etc.... 

我需要创建汇总统计如下图所示（摘要）

Year CountofCategoryA who started CountofCategoryB who started 
2003 
etc 

我可以进行更新生成上表对于每个单元格，在Access I中使用

UPDATE summary, 
     (A query that gives a count in a year) as counttab 
    SET summary.column = counttab.count 
WHERE summary.Year = currentyear 

我必须为每个单元格运行此查询是否存在更快/更高效的方式？

Answer 1

这听起来像你正在寻找一个交叉表查询：

TRANSFORM Count(*) AS Expr2 
SELECT Year([StartDate]) AS Expr1 
FROM SomeTable 
GROUP BY Year([StartDate]) 
PIVOT SomeTable.[Manager-category];