set @st_date = CURDATE();
with 
f as (
    SELECT Start_Date st,
            (LAG(end_date) over w) lend,
            End_Date
    FROM Projects
    Window w as (ORDER BY Start_Date)
),
f2 as (
    select
        if (f.lend = f.St, @st_date, @st_date := f.St) st,
        f.end_date end_date
    from f
)
select distinct
    f2.st, 
    MAX(f2.end_date) over start_d
from f2
window start_d as (partition by f2.st)
order by (count(*) over start_d), f2.st
;