Split time records across midnight

I’m trying to run some reports and having to deal with the whole issue of employee labor hours crossing midnight. It occurs to me though that I could split the records that cross midnight into two records as if the employee clocked out at midnight and simultaneously clocked back in at midnight thus avoiding the midnight problem altogether.

So if I have:

EmployeeId   InTime                     OutTime
---          -----------------------    -----------------------
1            2012-01-18 19:50:04.437    2012-01-19 03:30:02.433

What do you suppose would be the most elegant way to split this record like so:

EmployeeId   InTime                     OutTime
---          -----------------------    -----------------------
1            2012-01-18 19:50:04.437    2012-01-19 00:00:00.000
1            2012-01-19 00:00:00.000    2012-01-19 03:30:02.433

And yes, I have thoroughly thought through what effects this might have on existing functionality… which is why I’m opting to do this in a temporary table that will not affect existing functionality.

Answer

This might help:

DECLARE @tbl TABLE 
    (
        EmployeeId INT,
        InTime DATETIME,
        OutTime DATETIME
    )

INSERT INTO @tbl(EmployeeId,InTime,OutTime) VALUES (1,'2012-01-18 19:50:04.437','2012-01-19 03:30:02.433')
INSERT INTO @tbl(EmployeeId,InTime,OutTime) VALUES (2,'2012-01-18 19:50:04.437','2012-01-18 20:30:02.433')
INSERT INTO @tbl(EmployeeID,InTime,OutTime) VALUES (3,'2012-01-18 16:15:00.000','2012-01-19 00:00:00.000')
INSERT INTO @tbl(EmployeeID,InTime,OutTime) VALUES (4,'2012-01-18 00:00:00.000','2012-01-18 08:15:00.000')
SELECT
    tbl.EmployeeId,
    tbl.InTime,
    DATEADD(dd, DATEDIFF(dd, 0, tbl.OutTime), 0) AS OutTime
FROM
    @tbl AS tbl
WHERE
    DATEDIFF(dd,tbl.InTime,tbl.OutTime)=1
UNION ALL
SELECT
    tbl.EmployeeId,
    CASE WHEN DATEDIFF(dd,tbl.InTime,tbl.OutTime)=1
        THEN DATEADD(dd, DATEDIFF(dd, 0, tbl.OutTime), 0)
        ELSE tbl.InTime
    END AS InTime,
    tbl.OutTime
FROM @tbl AS tbl
ORDER BY EmployeeId