Find max value from coalesce function

This is my query:

declare @t table (date1 date,date2 date,date3 date)

insert into @t values ('2019-01-01','2019-01-20','2019-02-10')
insert into @t values (null,null,'2019-02-01')
insert into @t values (null,'2019-02-01','2019-02-02')

My expected output is:

2019-02-10  
2019-02-01  
2019-02-02

I tried to use coalesce like :

select coalesce(date1,date2,date3) as maxdate from @t

I know coalesce returns first not null value. So what I can do to get my desired result.

Answer

coalesce() has nothing to do with this. Unfortunately, SQL Server does not support greatest(). But you can use apply:

select t.*, m.max_date
from @t t cross apply
     (select max(dte) as max_date
      from (values (t.date1), (t.date2), (t.date3)) v(dte)
     ) m;

The max() ignores NULL values, so this does what you expect.

Here is a db<>fiddle.