Question

What is the most efficient way to select the first and last element only, from a column in SQLite?

Answer 1

The first and last element from a row?

SELECT column1, columnN FROM mytable; 

I think you must mean the first and last element from a column:

SELECT MIN(column1) AS First,        MAX(column1) AS Last FROM mytable; 

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See http://www.sqlite.org/lang_aggfunc.html for MIN() and MAX().

I’m using First and Last as column aliases.