如何发现员工部门变动？

Question

我有一个table，里面有各个员工的旧部门和新部门：

EmployeeID	OldDept	NewDept
123	Design	Design
234	Software	Engineering
345	Design	Software
456	Advertising	Software

如何创建如下所示的 table：

Dept	TransfersIn	TransfersOut
Software	2	1
Design	0	1
Advertising	0	1
Engineering	1	0

Answer 1

您也许可以使用此查询来查找转出：

SELECT 
    OldDept AS Dept,
    COUNTIF(OldDept != NewDept) As TransfersOut
FROM table
GROUPBY
    EmployeeID,
    OldDept,
    NewDept

Answer 2

下面使用

select * from (
  select NewDept as Department, count(*) Transfers, 'TransfersIn' Mode from your_table
  where NewDept != OldDept
  group by Department, Mode
  union all
  select OldDept as Department, count(*) Transfers, 'TransfersOut' Mode from your_table
  where NewDept != OldDept
  group by Department, Mode
)
pivot (sum(Transfers) for mode in ('TransfersIn', 'TransfersOut'))

如果应用于您问题中的示例数据 - 输出为

Answer 3

您可以使用两个子选择的 FULL OUTER JOIN

SELECT 
   COALESCE(OldDept,NewDept) AS Dept, IFNULL(TransfersIn,0) AS TransfersIn   , IFNULL(TransfersOut) AS TransfersOut
FROM
(SELECT NewDept, COUNT(*) AS TransfersIn FROM tabl1 GROUP BY NewDept) As Ne
FULL OUTER JOIN 
(SELECT OldDept, COUNT(*) AS TransfersOut FROM tabl1 GROUP BY NewDept) Ol
ON Ne.NewDept = Ol.OldDept

如何发现员工部门变动？

How to find employee department changes?

sql

google-bigquery