mysql - Select row based on max date across several columns -

for mysql database

i have table includes duplicate rows because of date values in several columns. looking select single row each unique customer id based on max date value evaluated across several date columns

[customer id, startdate, stopdate, modifydate, buydate]

for each customer id, i'd return row has maximum date either in startdate, stopdate, modifydate or buydate columns ( there nulls in date columns.

editing include example - sure how create table here:

*** edit

been trying quite awhile create table here example. can't figure out. posting image? desired rows returned indicated in red.

assuming values never null, can use greatest():

select t.* table t greatest(t.startdate, stopdate, buydate) =           (select max(greatest(t.startdate, stopdate, buydate))            t t2            t2.customerid = t.customerid           ); 

note: return multiple rows customer if more 1 row contains maximum date.