MySQL如何在一个集合中选择两个日志项之间的时间差？

我有一大组日志条目需要对其进行分析。我要做的是为每组日志选择开始和完成条目之间的时间差。我该怎么做呢

Sample Log Set:

ExecuteTime, Entry, TrackKey
7.2408730984, Start update, 487996b0608b0006bfbe5501217c76bde879b728
9.9038851261, Complete update, 487996b0608b0006bfbe5501217c76bde879b728

未经测试：

SELECT * FROM Table AS t1 LEFT JOIN (SELECT MIN(Sample) AS Min, MAX(Sample) AS Max FROM Table) AS t2 ON t1.TrackKey = t2.TrackKey

更新：

SELECT
    (t3.End - t2.Start) AS Total
FROM Table AS t1
    LEFT JOIN
    (
        SELECT
            Sample AS Start
        FROM
            Table
        WHERE
            Entry = "Start update"
    ) AS t2 ON t1.TrackKey = t2.TrackKey
LEFT JOIN
    (
        SELECT
            Sample AS End
        FROM
            Table
        WHERE
            Entry = "Complete update"
    ) AS t3 ON t1.TrackKey = t3.TrackKey

---

我假设开始时间是最小的，结束时间是最大的。如果不是这样，这个查询将是错误的

select TrackKey, (MAX(ExecuteTime) - MIN(ExecuteTime)) as time_difference
FROM table
WHERE Entry IN('Start update', 'Complete update')
GROUP BY TrackKey