[英]T-Sql get Employees Start and end dates on a yearly basis
我有一个名为“ Employee ”的表
员工表具有以下列
Id (Identity)
EmploymentStartDate (datetime),
EmploymentEndDate (nullable datetime)
T-SQL查询
DECLARE @FromYear int, @ToYear int
SELECT @FromYear = YEAR(MIN(EmploymentStartDate)),
@ToYear = YEAR(GETDATE())
FROM Employee
;WITH CTE AS
(
SELECT @FromYear As TheYear
UNION ALL
SELECT TheYear + 1
FROM CTE
WHERE TheYear < @ToYear
)
SELECT TheYear as [Year],
COUNT
(
CASE WHEN TheYear <= YEAR(COALESCE(EmploymentEndDate, GETDATE())) THEN
1
END
) As [EmployeeCountPerYear]
FROM CTE
INNER JOIN Employee ON(TheYear >= YEAR(EmploymentStartDate))
GROUP BY TheYear
题:
Employee表具有下面的行数据。
Id - EmploymentStartDate - EmploymentEndDate
1 - '2012-10-10' - null
2 - '2014-10-10' - '2015-10-10'
3 - '2015-10-10' - null
4 - '2016-10-10' - null
5 - '2017-10-10' - null
根据上表的行值结果应如下所示在我的查询中
TheYear - EmployeeCountPerYear
2012 - 1
2013 - 1
2014 - 2
2015 - 3 (Because EmploymentEndDate has one employee that worked in 2015)
2016 - 3
2017 - 4
但是,如果我运行查询,我将看不到上述结果。我不确定我能否说出问题,但我想逐年查找所有员工的工作开始日期和结束日期 。我们将不胜感激。谢谢。
您可以尝试OUTER APPLY
:
DECLARE @FromYear int, @ToYear int;
SELECT @FromYear = YEAR(MIN(EmploymentStartDate)),
@ToYear = YEAR(GETDATE())
FROM Employee;
WITH CTE AS
(
SELECT @FromYear As TheYear
UNION ALL
SELECT TheYear + 1
FROM CTE
WHERE TheYear < @ToYear
)
SELECT *
FROM CTE A
OUTER APPLY(SELECT COUNT(*) EmploymentStartDate
FROM dbo.Employee
WHERE A.TheYear
BETWEEN YEAR(EmploymentStartDate) AND YEAR(ISNULL(EmploymentEndDate,GETDATE()))) B;
这是一个演示 。 结果是:
╔═════════╦═════════════════════╗
║ TheYear ║ EmploymentStartDate ║
╠═════════╬═════════════════════╣
║ 2012 ║ 1 ║
║ 2013 ║ 1 ║
║ 2014 ║ 2 ║
║ 2015 ║ 3 ║
║ 2016 ║ 3 ║
║ 2017 ║ 4 ║
╚═════════╩═════════════════════╝
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