How do I address the last/first cell in a row|column?

[vek.m1234]

So how do I access the last cell in a column without hard-wiring it into the formula?
=SUM(G3:$???)
I don’t want to update my formula every time I add a new row.
=SUM(G3:ROW()-1) didn’t work

I am currently trying something like this
=ADDRESS(INDIRECT(“G” & “COLUMN()-3”))

Typically in awk/perl/Bash we’d use $1 $2 for fields and in vim $ or ^ or gg G as an addressing mechanism.

[vek.m1234]

=SUM(G3:INDIRECT(ADDRESS(ROW()-1, COLUMN())))

ROW(), COLUMN() return integer positions, ADDRESS converts it into text (A1 etc) and INDIRECT takes text-addresses and returns a reference to the cell. SUM(G3:reference-to-cell)