Most efficient way to select 1st and last element, SQLite?

Question

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

Thanks.

Answer 1

Probably like this:

SELECT dbo.Table.FirstCol, dbo.Table.LastCol FROM Table

You get minor efficiency enhancements from specifying the table name and schema.

Answer 2

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.

Answer 3

The most efficient way would be to know what those fields were called and simply select them.

SELECT `first_field`, `last_field` FROM `table`;

Answer 4

if it's just one column:

SELECT min(column) as first, max(column) as last FROM table

if you want to select whole row:

SELECT 'first',* FROM table ORDER BY column DESC LIMIT 1
UNION 
SELECT 'last',* FROM table ORDER BY column ASC LIMIT 1