How Can I Detect and Bound Changes Between Row Values in a SQL Table?

Question

I have a table which records values over time, similar to the following:

RecordId  Time   Name
========================
1         10     Running
2         18         


        

Answer 1

Here's a CTE solution that gets the results you're seeking:

;WITH TheRecords (FirstTime,SecondTime,[Name])
AS
(
    SELECT [Time],
    (
        SELECT MIN([Time]) 
        FROM ActivityTable at2
        WHERE at2.[Time]>at.[Time]
        AND at2.[Name]<>at.[Name]
    ),
    [Name]
    FROM ActivityTable at
)
SELECT MIN(FirstTime) AS FromTime,SecondTime AS ToTime,MIN([Name]) AS [Name]
FROM TheRecords
GROUP BY SecondTime
ORDER BY FromTime,ToTime