only last records in subgroups

Hi there,

I'm having hard times with the following query:
I want to select only the last records from a subgroup
in a table. But because the subgroup contains
different number of records for every id, I don't know
how to specify that. For example, check the following
table,
id, day
x,300
x,250,
x,0
y,250
y,4

I only want the records
x,0 and y,4 but how do I manage this in sql? I was
hoping for a keyword LAST or so, where I can specify
that when I've ordered my results with order by, I
could only get the last of the subgroups (the first
one is easy because I could use limit 1)

Thanks in advance

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