Question

表1

ID product

001 LG
001 Sony
001 LG
001 LG
001 Sony
001 BPL
001 BPL
001 Samsung
002 LG
002 BPL
002 LG
...,

我想为每个人都计算每个产品的数量。

预期产出

ID BPL LG Samsung Sony

001 2 3 1 2
002 1 1 0 0
..,

如何查询每个人员的每个产品计数。

需要SQL查询帮助。

Answer 1

Select ID
        , Sum( Case When Product = 'BPL' Then 1 Else 0 End ) As BPL
        , Sum( Case When Product = 'Sony' Then 1 Else 0 End ) As Sony
        , Sum( Case When Product = 'LG' Then 1 Else 0 End ) As LG
        , Sum( Case When Product = 'Samsung' Then 1 Else 0 End ) As Samsung
From Table
Group By ID

这是一个典型的交叉表问题。您可以谷歌获得许多类似的答案。

Answer 2

使用PIVOT命令：

看看这个例子：

SELECT s.Name ShiftName,

h.BusinessEntityID,

d.Name DepartmentName

FROM HumanResources.EmployeeDepartmentHistory h

INNER JOIN HumanResources.Department d ON

h.DepartmentID = d.DepartmentID

INNER JOIN HumanResources.Shift s ON

h.ShiftID = s.ShiftID

WHERE EndDate IS NULL AND

d.Name IN ('Production', 'Engineering', 'Marketing')

ORDER BY ShiftName

此查询的返回表：

ShiftName   BusinessEntityID   DepartmentName
Day              3                            Engineering
Day              9                            Engineering
...
Day              2                            Marketing
Day              6                            Marketing
...
Evening          25                          Production
Evening          18                          Production
Night            14                          Production
Night            27                          Production
...
Night            252                        Production
(194 row(s) affected)

现在您可以更改返回表格的格式：

SELECT ShiftName,

Production,

Engineering,

Marketing

FROM

(SELECT s.Name ShiftName,

h.BusinessEntityID,

d.Name DepartmentName

FROM HumanResources.EmployeeDepartmentHistory h

INNER JOIN HumanResources.Department d ON

h.DepartmentID = d.DepartmentID

INNER JOIN HumanResources.Shift s ON

h.ShiftID = s.ShiftID

WHERE EndDate IS NULL AND

d.Name IN ('Production', 'Engineering', 'Marketing')) AS a

PIVOT

(

COUNT(BusinessEntityID)

FOR DepartmentName IN ([Production], [Engineering], [Marketing])

) AS b

ORDER BY ShiftName

返回的表格如下：

ShiftName   Production   Engineering   Marketing
Day              79                 6                    9
Evening          54                 0                    0
Night            46                 0                    0

(3 row(s) affected)

Answer 3

通常，您不能这样做，因为输出中的列数取决于产品列中存储的不同值的数量。如果您事先知道所有可能的产品，您可以像在@Thomas的回答中那样将它们硬编码到查询中。否则，你能做的最好的是：

Select ID, product, count(*) as cnt
From Table1
Group By ID, product

这会产生如下表格：

ID  product cnt

001 LG      3
001 Sony    2
001 BPL     1
001 Samsung 1
002 LG      2
002 BPL     1

计算每个ID的每个产品

3 个答案: