Las siguientes secciones describen las funciones de navegación que admite BigQuery. Las funciones de navegación son un subconjunto de funciones analíticas. Para obtener una explicación de cómo funcionan las funciones analíticas, consulta conceptos de funciones analíticas. Para obtener una explicación de cómo funcionan las funciones de navegación, consulta conceptos de funciones de navegación.
FIRST_VALUE
FIRST_VALUE (value_expression [{RESPECT | IGNORE} NULLS])
Descripción
Muestra el valor de value_expression
de la primera fila en el marco de la ventana actual.
Esta función incluye valores NULL
en el cálculo, a menos que IGNORE NULLS
esté presente. Si IGNORE NULLS
está presente, la función excluye los valores NULL
del cálculo.
Tipos de argumentos admitidos
value_expression
puede ser cualquier tipo de datos que una expresión puede mostrar.
Tipo de datos que se muestran
CUALQUIERA
Ejemplos
El siguiente ejemplo procesa el tiempo más rápido para cada división.
WITH finishers AS
(SELECT 'Sophia Liu' as name,
TIMESTAMP '2016-10-18 2:51:45' as finish_time,
'F30-34' as division
UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
FORMAT_TIMESTAMP('%X', finish_time) AS finish_time,
division,
FORMAT_TIMESTAMP('%X', fastest_time) AS fastest_time,
TIMESTAMP_DIFF(finish_time, fastest_time, SECOND) AS delta_in_seconds
FROM (
SELECT name,
finish_time,
division,
FIRST_VALUE(finish_time)
OVER (PARTITION BY division ORDER BY finish_time ASC
ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS fastest_time
FROM finishers);
+-----------------+-------------+----------+--------------+------------------+
| name | finish_time | division | fastest_time | delta_in_seconds |
+-----------------+-------------+----------+--------------+------------------+
| Carly Forte | 03:08:58 | F25-29 | 03:08:58 | 0 |
| Sophia Liu | 02:51:45 | F30-34 | 02:51:45 | 0 |
| Nikki Leith | 02:59:01 | F30-34 | 02:51:45 | 436 |
| Jen Edwards | 03:06:36 | F30-34 | 02:51:45 | 891 |
| Meghan Lederer | 03:07:41 | F30-34 | 02:51:45 | 956 |
| Lauren Reasoner | 03:10:14 | F30-34 | 02:51:45 | 1109 |
| Lisa Stelzner | 02:54:11 | F35-39 | 02:54:11 | 0 |
| Lauren Matthews | 03:01:17 | F35-39 | 02:54:11 | 426 |
| Desiree Berry | 03:05:42 | F35-39 | 02:54:11 | 691 |
| Suzy Slane | 03:06:24 | F35-39 | 02:54:11 | 733 |
+-----------------+-------------+----------+--------------+------------------+
LAST_VALUE
LAST_VALUE (value_expression [{RESPECT | IGNORE} NULLS])
Descripción
Muestra el valor de value_expression
de la última fila en el marco de la ventana actual.
Esta función incluye valores NULL
en el cálculo, a menos que IGNORE NULLS
esté presente. Si IGNORE NULLS
está presente, la función excluye los valores NULL
del cálculo.
Tipos de argumentos admitidos
value_expression
puede ser cualquier tipo de datos que una expresión puede mostrar.
Tipo de datos que se muestran
CUALQUIERA
Ejemplos
El siguiente ejemplo procesa el tiempo más lento para cada división.
WITH finishers AS
(SELECT 'Sophia Liu' as name,
TIMESTAMP '2016-10-18 2:51:45' as finish_time,
'F30-34' as division
UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
FORMAT_TIMESTAMP('%X', finish_time) AS finish_time,
division,
FORMAT_TIMESTAMP('%X', slowest_time) AS slowest_time,
TIMESTAMP_DIFF(slowest_time, finish_time, SECOND) AS delta_in_seconds
FROM (
SELECT name,
finish_time,
division,
LAST_VALUE(finish_time)
OVER (PARTITION BY division ORDER BY finish_time ASC
ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS slowest_time
FROM finishers);
+-----------------+-------------+----------+--------------+------------------+
| name | finish_time | division | slowest_time | delta_in_seconds |
+-----------------+-------------+----------+--------------+------------------+
| Carly Forte | 03:08:58 | F25-29 | 03:08:58 | 0 |
| Sophia Liu | 02:51:45 | F30-34 | 03:10:14 | 1109 |
| Nikki Leith | 02:59:01 | F30-34 | 03:10:14 | 673 |
| Jen Edwards | 03:06:36 | F30-34 | 03:10:14 | 218 |
| Meghan Lederer | 03:07:41 | F30-34 | 03:10:14 | 153 |
| Lauren Reasoner | 03:10:14 | F30-34 | 03:10:14 | 0 |
| Lisa Stelzner | 02:54:11 | F35-39 | 03:06:24 | 733 |
| Lauren Matthews | 03:01:17 | F35-39 | 03:06:24 | 307 |
| Desiree Berry | 03:05:42 | F35-39 | 03:06:24 | 42 |
| Suzy Slane | 03:06:24 | F35-39 | 03:06:24 | 0 |
+-----------------+-------------+----------+--------------+------------------+
NTH_VALUE
NTH_VALUE (value_expression, constant_integer_expression [{RESPECT | IGNORE} NULLS])
Descripción
Muestra el valor de value_expression
en la enésima (Nth) fila del marco de la ventana actual, en la que Nth se define mediante constant_integer_expression
. Muestra NULL si no hay tal fila.
Esta función incluye valores NULL
en el cálculo, a menos que IGNORE NULLS
esté presente. Si IGNORE NULLS
está presente, la función excluye los valores NULL
del cálculo.
Tipos de argumentos admitidos
value_expression
puede ser cualquier tipo de datos que pueda mostrarse a partir de una expresión.constant_integer_expression
puede ser cualquier expresión constante que muestre un número entero.
Tipo de datos que se muestran
CUALQUIERA
Ejemplos
WITH finishers AS
(SELECT 'Sophia Liu' as name,
TIMESTAMP '2016-10-18 2:51:45' as finish_time,
'F30-34' as division
UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
FORMAT_TIMESTAMP('%X', finish_time) AS finish_time,
division,
FORMAT_TIMESTAMP('%X', fastest_time) AS fastest_time,
FORMAT_TIMESTAMP('%X', second_fastest) AS second_fastest
FROM (
SELECT name,
finish_time,
division,finishers,
FIRST_VALUE(finish_time)
OVER w1 AS fastest_time,
NTH_VALUE(finish_time, 2)
OVER w1 as second_fastest
FROM finishers
WINDOW w1 AS (
PARTITION BY division ORDER BY finish_time ASC
ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING));
+-----------------+-------------+----------+--------------+----------------+
| name | finish_time | division | fastest_time | second_fastest |
+-----------------+-------------+----------+--------------+----------------+
| Carly Forte | 03:08:58 | F25-29 | 03:08:58 | NULL |
| Sophia Liu | 02:51:45 | F30-34 | 02:51:45 | 02:59:01 |
| Nikki Leith | 02:59:01 | F30-34 | 02:51:45 | 02:59:01 |
| Jen Edwards | 03:06:36 | F30-34 | 02:51:45 | 02:59:01 |
| Meghan Lederer | 03:07:41 | F30-34 | 02:51:45 | 02:59:01 |
| Lauren Reasoner | 03:10:14 | F30-34 | 02:51:45 | 02:59:01 |
| Lisa Stelzner | 02:54:11 | F35-39 | 02:54:11 | 03:01:17 |
| Lauren Matthews | 03:01:17 | F35-39 | 02:54:11 | 03:01:17 |
| Desiree Berry | 03:05:42 | F35-39 | 02:54:11 | 03:01:17 |
| Suzy Slane | 03:06:24 | F35-39 | 02:54:11 | 03:01:17 |
+-----------------+-------------+----------+--------------+----------------+
LEAD
LEAD (value_expression[, offset [, default_expression]])
Descripción
Muestra el valor de value_expression
en una fila posterior. Cuando se cambia el valor de offset
, cambia la fila siguiente que se muestra; el valor predeterminado es 1
, que indica la siguiente fila en el marco de la ventana. Si offset
es NULL o un valor negativo, se produce un error.
Se usa la default_expression
opcional si no hay una fila en el marco de la ventana del desplazamiento especificado. Esta expresión debe ser constante y su tipo debe ser coercible implícitamente al tipo de value_expression
. Si no se especifica, default_expression
queda predeterminada en NULL.
Tipos de argumentos admitidos
value_expression
puede ser cualquier tipo de datos que pueda mostrarse a partir de una expresión.offset
debe ser un literal o parámetro de número entero no negativo.default_expression
debe ser compatible con el tipo de expresión de valor.
Tipo de datos que se muestran
CUALQUIERA
Ejemplos
El siguiente ejemplo ilustra un uso básico de la función LEAD
.
WITH finishers AS
(SELECT 'Sophia Liu' as name,
TIMESTAMP '2016-10-18 2:51:45' as finish_time,
'F30-34' as division
UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
finish_time,
division,
LEAD(name)
OVER (PARTITION BY division ORDER BY finish_time ASC) AS followed_by
FROM finishers;
+-----------------+-------------+----------+-----------------+
| name | finish_time | division | followed_by |
+-----------------+-------------+----------+-----------------+
| Carly Forte | 03:08:58 | F25-29 | NULL |
| Sophia Liu | 02:51:45 | F30-34 | Nikki Leith |
| Nikki Leith | 02:59:01 | F30-34 | Jen Edwards |
| Jen Edwards | 03:06:36 | F30-34 | Meghan Lederer |
| Meghan Lederer | 03:07:41 | F30-34 | Lauren Reasoner |
| Lauren Reasoner | 03:10:14 | F30-34 | NULL |
| Lisa Stelzner | 02:54:11 | F35-39 | Lauren Matthews |
| Lauren Matthews | 03:01:17 | F35-39 | Desiree Berry |
| Desiree Berry | 03:05:42 | F35-39 | Suzy Slane |
| Suzy Slane | 03:06:24 | F35-39 | NULL |
+-----------------+-------------+----------+-----------------+
El siguiente ejemplo usa el parámetro opcional offset
.
WITH finishers AS
(SELECT 'Sophia Liu' as name,
TIMESTAMP '2016-10-18 2:51:45' as finish_time,
'F30-34' as division
UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
finish_time,
division,
LEAD(name, 2)
OVER (PARTITION BY division ORDER BY finish_time ASC) AS two_runners_back
FROM finishers;
+-----------------+-------------+----------+------------------+
| name | finish_time | division | two_runners_back |
+-----------------+-------------+----------+------------------+
| Carly Forte | 03:08:58 | F25-29 | NULL |
| Sophia Liu | 02:51:45 | F30-34 | Jen Edwards |
| Nikki Leith | 02:59:01 | F30-34 | Meghan Lederer |
| Jen Edwards | 03:06:36 | F30-34 | Lauren Reasoner |
| Meghan Lederer | 03:07:41 | F30-34 | NULL |
| Lauren Reasoner | 03:10:14 | F30-34 | NULL |
| Lisa Stelzner | 02:54:11 | F35-39 | Desiree Berry |
| Lauren Matthews | 03:01:17 | F35-39 | Suzy Slane |
| Desiree Berry | 03:05:42 | F35-39 | NULL |
| Suzy Slane | 03:06:24 | F35-39 | NULL |
+-----------------+-------------+----------+------------------+
El siguiente ejemplo reemplaza los valores NULL por un valor predeterminado.
WITH finishers AS
(SELECT 'Sophia Liu' as name,
TIMESTAMP '2016-10-18 2:51:45' as finish_time,
'F30-34' as division
UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
finish_time,
division,
LEAD(name, 2, 'Nobody')
OVER (PARTITION BY division ORDER BY finish_time ASC) AS two_runners_back
FROM finishers;
+-----------------+-------------+----------+------------------+
| name | finish_time | division | two_runners_back |
+-----------------+-------------+----------+------------------+
| Carly Forte | 03:08:58 | F25-29 | Nobody |
| Sophia Liu | 02:51:45 | F30-34 | Jen Edwards |
| Nikki Leith | 02:59:01 | F30-34 | Meghan Lederer |
| Jen Edwards | 03:06:36 | F30-34 | Lauren Reasoner |
| Meghan Lederer | 03:07:41 | F30-34 | Nobody |
| Lauren Reasoner | 03:10:14 | F30-34 | Nobody |
| Lisa Stelzner | 02:54:11 | F35-39 | Desiree Berry |
| Lauren Matthews | 03:01:17 | F35-39 | Suzy Slane |
| Desiree Berry | 03:05:42 | F35-39 | Nobody |
| Suzy Slane | 03:06:24 | F35-39 | Nobody |
+-----------------+-------------+----------+------------------+
LAG
LAG (value_expression[, offset [, default_expression]])
Descripción
Muestra el valor de value_expression
en una fila anterior. Cuando se cambia el valor de offset
, cambia la fila anterior que se muestra; el valor predeterminado es 1
, que indica la fila anterior en el marco de la ventana. Si offset
es NULL o un valor negativo, se produce un error.
Se usa la default_expression
opcional si no hay una fila en el marco de la ventana del desplazamiento especificado. Esta expresión debe ser constante y su tipo debe ser coercible implícitamente al tipo de value_expression
. Si no se especifica, default_expression
queda predeterminada en NULL.
Tipos de argumentos admitidos
value_expression
puede ser cualquier tipo de datos que pueda mostrarse a partir de una expresión.offset
debe ser un literal o parámetro de número entero no negativo.default_expression
debe ser compatible con el tipo de expresión de valor.
Tipo de datos que se muestran
CUALQUIERA
Ejemplos
El siguiente ejemplo ilustra un uso básico de la función LAG
.
WITH finishers AS
(SELECT 'Sophia Liu' as name,
TIMESTAMP '2016-10-18 2:51:45' as finish_time,
'F30-34' as division
UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
finish_time,
division,
LAG(name)
OVER (PARTITION BY division ORDER BY finish_time ASC) AS preceding_runner
FROM finishers;
+-----------------+-------------+----------+------------------+
| name | finish_time | division | preceding_runner |
+-----------------+-------------+----------+------------------+
| Carly Forte | 03:08:58 | F25-29 | NULL |
| Sophia Liu | 02:51:45 | F30-34 | NULL |
| Nikki Leith | 02:59:01 | F30-34 | Sophia Liu |
| Jen Edwards | 03:06:36 | F30-34 | Nikki Leith |
| Meghan Lederer | 03:07:41 | F30-34 | Jen Edwards |
| Lauren Reasoner | 03:10:14 | F30-34 | Meghan Lederer |
| Lisa Stelzner | 02:54:11 | F35-39 | NULL |
| Lauren Matthews | 03:01:17 | F35-39 | Lisa Stelzner |
| Desiree Berry | 03:05:42 | F35-39 | Lauren Matthews |
| Suzy Slane | 03:06:24 | F35-39 | Desiree Berry |
+-----------------+-------------+----------+------------------+
El siguiente ejemplo usa el parámetro opcional offset
.
WITH finishers AS
(SELECT 'Sophia Liu' as name,
TIMESTAMP '2016-10-18 2:51:45' as finish_time,
'F30-34' as division
UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
finish_time,
division,
LAG(name, 2)
OVER (PARTITION BY division ORDER BY finish_time ASC) AS two_runners_ahead
FROM finishers;
+-----------------+-------------+----------+-------------------+
| name | finish_time | division | two_runners_ahead |
+-----------------+-------------+----------+-------------------+
| Carly Forte | 03:08:58 | F25-29 | NULL |
| Sophia Liu | 02:51:45 | F30-34 | NULL |
| Nikki Leith | 02:59:01 | F30-34 | NULL |
| Jen Edwards | 03:06:36 | F30-34 | Sophia Liu |
| Meghan Lederer | 03:07:41 | F30-34 | Nikki Leith |
| Lauren Reasoner | 03:10:14 | F30-34 | Jen Edwards |
| Lisa Stelzner | 02:54:11 | F35-39 | NULL |
| Lauren Matthews | 03:01:17 | F35-39 | NULL |
| Desiree Berry | 03:05:42 | F35-39 | Lisa Stelzner |
| Suzy Slane | 03:06:24 | F35-39 | Lauren Matthews |
+-----------------+-------------+----------+-------------------+
El siguiente ejemplo reemplaza los valores NULL por un valor predeterminado.
WITH finishers AS
(SELECT 'Sophia Liu' as name,
TIMESTAMP '2016-10-18 2:51:45' as finish_time,
'F30-34' as division
UNION ALL SELECT 'Lisa Stelzner', TIMESTAMP '2016-10-18 2:54:11', 'F35-39'
UNION ALL SELECT 'Nikki Leith', TIMESTAMP '2016-10-18 2:59:01', 'F30-34'
UNION ALL SELECT 'Lauren Matthews', TIMESTAMP '2016-10-18 3:01:17', 'F35-39'
UNION ALL SELECT 'Desiree Berry', TIMESTAMP '2016-10-18 3:05:42', 'F35-39'
UNION ALL SELECT 'Suzy Slane', TIMESTAMP '2016-10-18 3:06:24', 'F35-39'
UNION ALL SELECT 'Jen Edwards', TIMESTAMP '2016-10-18 3:06:36', 'F30-34'
UNION ALL SELECT 'Meghan Lederer', TIMESTAMP '2016-10-18 3:07:41', 'F30-34'
UNION ALL SELECT 'Carly Forte', TIMESTAMP '2016-10-18 3:08:58', 'F25-29'
UNION ALL SELECT 'Lauren Reasoner', TIMESTAMP '2016-10-18 3:10:14', 'F30-34')
SELECT name,
finish_time,
division,
LAG(name, 2, 'Nobody')
OVER (PARTITION BY division ORDER BY finish_time ASC) AS two_runners_ahead
FROM finishers;
+-----------------+-------------+----------+-------------------+
| name | finish_time | division | two_runners_ahead |
+-----------------+-------------+----------+-------------------+
| Carly Forte | 03:08:58 | F25-29 | Nobody |
| Sophia Liu | 02:51:45 | F30-34 | Nobody |
| Nikki Leith | 02:59:01 | F30-34 | Nobody |
| Jen Edwards | 03:06:36 | F30-34 | Sophia Liu |
| Meghan Lederer | 03:07:41 | F30-34 | Nikki Leith |
| Lauren Reasoner | 03:10:14 | F30-34 | Jen Edwards |
| Lisa Stelzner | 02:54:11 | F35-39 | Nobody |
| Lauren Matthews | 03:01:17 | F35-39 | Nobody |
| Desiree Berry | 03:05:42 | F35-39 | Lisa Stelzner |
| Suzy Slane | 03:06:24 | F35-39 | Lauren Matthews |
+-----------------+-------------+----------+-------------------+
PERCENTILE_CONT
PERCENTILE_CONT (value_expression, percentile [{RESPECT | IGNORE} NULLS])
Descripción
Calcula el valor de percentil especificado para value_expression con interpolación lineal.
Esta función ignora los valores NULL si RESPECT NULLS
está ausente. Si RESPECT
NULLS
está presente:
- La interpolación entre dos valores
NULL
muestraNULL
. - La interpolación entre un valor
NULL
y un valor noNULL
muestra el valor noNULL
.
Tipos de argumentos admitidos
value_expression
es una expresión numérica.percentile
es un literalDOUBLE
en el rango[0, 1]
.
Tipo de datos que se muestran
DOUBLE
Ejemplos
El siguiente ejemplo procesa el valor para algunos percentiles de una columna de valores a la vez que ignora los valores nulos.
SELECT
PERCENTILE_CONT(x, 0) OVER() AS min,
PERCENTILE_CONT(x, 0.01) OVER() AS percentile1,
PERCENTILE_CONT(x, 0.5) OVER() AS median,
PERCENTILE_CONT(x, 0.9) OVER() AS percentile90,
PERCENTILE_CONT(x, 1) OVER() AS max
FROM UNNEST([0, 3, NULL, 1, 2]) AS x LIMIT 1;
+-----+-------------+--------+--------------+-----+
| min | percentile1 | median | percentile90 | max |
+-----+-------------+--------+--------------+-----+
| 0 | 0.03 | 1.5 | 2.7 | 3 |
+-----+-------------+--------+--------------+-----+
El siguiente ejemplo procesa el valor de algunos percentiles a partir de una columna de valores y respeta los valores nulos.
SELECT
PERCENTILE_CONT(x, 0 RESPECT NULLS) OVER() AS min,
PERCENTILE_CONT(x, 0.01 RESPECT NULLS) OVER() AS percentile1,
PERCENTILE_CONT(x, 0.5 RESPECT NULLS) OVER() AS median,
PERCENTILE_CONT(x, 0.9 RESPECT NULLS) OVER() AS percentile90,
PERCENTILE_CONT(x, 1 RESPECT NULLS) OVER() AS max
FROM UNNEST([0, 3, NULL, 1, 2]) AS x LIMIT 1;
+------+-------------+--------+--------------+-----+
| min | percentile1 | median | percentile90 | max |
+------+-------------+--------+--------------+-----+
| NULL | 0 | 1 | 2.6 | 3 |
+------+-------------+--------+--------------+-----+
PERCENTILE_DISC
PERCENTILE_DISC (value_expression, percentile [{RESPECT | IGNORE} NULLS])
Descripción
Procesa el valor de percentil especificado para una value_expression
discreta. El valor mostrado es el primer valor ordenado de value_expression
con una distribución acumulada mayor o igual al valor de percentile
dado.
A menos que RESPECT NULLS
esté presente, esta función ignora los valores NULL
.
Tipos de argumentos admitidos
value_expression
puede ser cualquier tipo ordenable.percentile
es un literalDOUBLE
en el rango[0, 1]
.
Tipo de datos que se muestran
ANY
Ejemplos
El siguiente ejemplo procesa el valor para algunos percentiles de una columna de valores a la vez que ignora los valores nulos.
SELECT
x,
PERCENTILE_DISC(x, 0) OVER() AS min,
PERCENTILE_DISC(x, 0.5) OVER() AS median,
PERCENTILE_DISC(x, 1) OVER() AS max
FROM UNNEST(['c', NULL, 'b', 'a']) AS x;
+------+-----+--------+-----+
| x | min | median | max |
+------+-----+--------+-----+
| c | a | b | c |
| NULL | a | b | c |
| b | a | b | c |
| a | a | b | c |
+------+-----+--------+-----+
El siguiente ejemplo procesa el valor de algunos percentiles a partir de una columna de valores y respeta los valores nulos.
SELECT
x,
PERCENTILE_DISC(x, 0 RESPECT NULLS) OVER() AS min,
PERCENTILE_DISC(x, 0.5 RESPECT NULLS) OVER() AS median,
PERCENTILE_DISC(x, 1 RESPECT NULLS) OVER() AS max
FROM UNNEST(['c', NULL, 'b', 'a']) AS x;
+------+------+--------+-----+
| x | min | median | max |
+------+------+--------+-----+
| c | NULL | a | c |
| NULL | NULL | a | c |
| b | NULL | a | c |
| a | NULL | a | c |
+------+------+--------+-----+