Traer solamente el 1er registro.

Usaremos tres maneras diferentes con FETCH, LIMIT y WINDOW FUNCTION:

CLASE

FECTH

SELECT *
FROM platzi.alumnos
FETCH FIRST 1 ROWS ONLY;

RETO

Los 5 primeros registros.

FETCH

SELECT *
FROM platzi.alumnos
FETCH FIRST 5 ROWS ONLY;

BETWEEN

SELECT * 
FROM platzi.alumnos
WHERE id BETWEEN 1 AND 5;

AND

SELECT * 
FROM platzi.alumnos
WHERE id>=1 AND id<=5;

LIMIT

SELECT *
FROM platzi.alumnos
LIMIT 1;

LIMIT

SELECT *
FROM platzi.alumnos
LIMIT 5;

WHERE

SELECT * 
FROM platzi.alumnos
WHERE id <= 5;

WINDOW FUNCTION

SELECT *
FROM  (
	SELECT ROW_NUMBER() OVER() AS row_id, *
	FROM platzi.alumnos
	) AS alumnos_with_row_num
WHERE row_id = 1;

WINDOW FUNCTION

SELECT *
FROM  (
	SELECT ROW_NUMBER() OVER() AS row_id, *
	FROM platzi.alumnos
) AS alumnos_with_row_num
WHERE row_id <= 5;