PostgreSQL – Función ROW_NUMBER

En ROW_NUMBER()

ROW_NUMBER() OVER(
    [PARTITION BY column_1, column_2, …]
    [ORDER BY column_3, column_4, …]
)

Analicemos la sintaxis anterior:

• NUMERO DE FILA()
• PARTICIÓN POR
• PEDIR POR ÚLTIMO

CREATE TABLE Animal_groups (
    animal_id serial PRIMARY KEY,
    animal_name VARCHAR (255) NOT NULL
);

CREATE TABLE Mammals (
    mammal_id serial PRIMARY KEY,
    mammal_name VARCHAR (255) NOT NULL,
    lifespan DECIMAL (11, 2),
    animal_id INT NOT NULL,
    FOREIGN KEY (animal_id) REFERENCES Animal_groups (animal_id)
);

Ahora añádele algunos datos:

INSERT INTO Animal_groups (animal_name)
VALUES
    ('Terrestrial'),
    ('Aquatic'),
    ('Winged');

INSERT INTO Mammals(mammal_name, animal_id, lifespan)
VALUES
    ('Cow', 1, 10),
    ('Dog', 1, 7),
    ('Ox', 1, 13),
    ('Wolf', 1, 11),
    ('Blue Whale', 2, 80),
    ('Dolphin', 2, 5),
    ('Sea Horse', 2, 3),
    ('Octopus', 2, 8),
    ('Bat', 3, 4),
    ('Flying Squirrels', 3, 1),
    ('Petaurus', 3, 2);

ORDEN BYROW_NUMBER()

SELECT
    mammal_id,
    mammal_name,
    animal_id,
    ROW_NUMBER () OVER (
           ORDER BY mammal_name
        )
FROM
    Mammals;

Producción:

Ejemplo 2:

ROW_NUMBER()productos

SELECT DISTINCT
    lifespan,
    ROW_NUMBER () OVER (ORDER BY lifespan)
FROM
    Mammals
ORDER BY
    lifespan;

Producción: