MySQL 从只有开始日期的两个连续行中导出结束日期

Question

I have a table like the one below:

I have tried this, but it doesn't work:

SELECT A.id, cast(A.startdate as date) as from_date, cast(B.startdate as date)
AS enddate
 FROM three A INNER JOIN three B ON B.id = (A.id)
ORDER BY A.id,cast(A.startdate as date) ASC

My desired result should be:

Answer 1

I think this is what you want:

SELECT
    t.Id,
    t.old_value,
    t.new_value,
    t.StartDate,
    -- if it's the latest entry of distinct old_value new_value pairs
    IF(t1.Id IS NULL, t2.StartDate - INTERVAL 1 DAY, t.StartDate) AS EndDate
FROM three t
LEFT JOIN three t1 ON t.old_value = t1.old_value AND t.new_value = t1.new_value
    AND t.StartDate > t1.StartDate
LEFT JOIN three t2 ON t.new_value = t2.old_value
;

Hard to tell without show creates and usable sample data.