In SQL, what’s the difference between count(column) and count(*)?

by

count(*) counts NULLs and count(column) does not

[edit] added this code so that people can run it

create table #bla(id int,id2 int)
insert #bla values(null,null)
insert #bla values(1,null)
insert #bla values(null,1)
insert #bla values(1,null)
insert #bla values(null,1)
insert #bla values(1,null)
insert #bla values(null,null)

select count(*),count(id),count(id2)
from #bla

results
7 3 2

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