Navigation functions

GoogleSQL for BigQuery supports navigation functions. Navigation functions are a subset of window functions. To create a window function call and learn about the syntax for window functions, see Window function_calls.

Navigation functions generally compute some value_expression over a different row in the window frame from the current row. The OVER clause syntax varies across navigation functions.

For all navigation functions, the result data type is the same type as value_expression.

Function list

Name Summary
FIRST_VALUE Gets a value for the first row in the current window frame.
LAG Gets a value for a preceding row.
LAST_VALUE Gets a value for the last row in the current window frame.
LEAD Gets a value for a subsequent row.
NTH_VALUE Gets a value for the Nth row of the current window frame.
PERCENTILE_CONT Computes the specified percentile for a value, using linear interpolation.
PERCENTILE_DISC Computes the specified percentile for a discrete value.

FIRST_VALUE

FIRST_VALUE(value_expression[{RESPECT|IGNORE}NULLS])
OVERover_clause
over_clause:
{named_window|([window_specification])}
window_specification:
[named_window]
[PARTITIONBYpartition_expression[,...]]
ORDERBYexpression[{ASC|DESC}][,...]
[window_frame_clause]

Description

Returns the value of the value_expression for the first row in the current window frame.

This function includes NULL values in the calculation unless IGNORE NULLS is present. If IGNORE NULLS is present, the function excludes NULL values from the calculation.

To learn more about the OVER clause and how to use it, see Window function calls.

Supported Argument Types

value_expression can be any data type that an expression can return.

Return Data Type

Same type as value_expression.

Examples

The following example computes the fastest time for each division.

WITHfinishersAS
(SELECT'Sophia Liu'asname,
TIMESTAMP'2016-10-18 2:51:45'asfinish_time,
'F30-34'asdivision
UNIONALLSELECT'Lisa Stelzner',TIMESTAMP'2016-10-18 2:54:11','F35-39'
UNIONALLSELECT'Nikki Leith',TIMESTAMP'2016-10-18 2:59:01','F30-34'
UNIONALLSELECT'Lauren Matthews',TIMESTAMP'2016-10-18 3:01:17','F35-39'
UNIONALLSELECT'Desiree Berry',TIMESTAMP'2016-10-18 3:05:42','F35-39'
UNIONALLSELECT'Suzy Slane',TIMESTAMP'2016-10-18 3:06:24','F35-39'
UNIONALLSELECT'Jen Edwards',TIMESTAMP'2016-10-18 3:06:36','F30-34'
UNIONALLSELECT'Meghan Lederer',TIMESTAMP'2016-10-18 3:07:41','F30-34'
UNIONALLSELECT'Carly Forte',TIMESTAMP'2016-10-18 3:08:58','F25-29'
UNIONALLSELECT'Lauren Reasoner',TIMESTAMP'2016-10-18 3:10:14','F30-34')
SELECTname,
FORMAT_TIMESTAMP('%X',finish_time)ASfinish_time,
division,
FORMAT_TIMESTAMP('%X',fastest_time)ASfastest_time,
TIMESTAMP_DIFF(finish_time,fastest_time,SECOND)ASdelta_in_seconds
FROM(
SELECTname,
finish_time,
division,
FIRST_VALUE(finish_time)
OVER(PARTITIONBYdivisionORDERBYfinish_timeASC
ROWSBETWEENUNBOUNDEDPRECEDINGANDUNBOUNDEDFOLLOWING)ASfastest_time
FROMfinishers);
/*-----------------+-------------+----------+--------------+------------------*
 | 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 |
 *-----------------+-------------+----------+--------------+------------------*/

LAG

LAG(value_expression[,offset[,default_expression]])
OVERover_clause
over_clause:
{named_window|([window_specification])}
window_specification:
[named_window]
[PARTITIONBYpartition_expression[,...]]
ORDERBYexpression[{ASC|DESC}][,...]

Description

Returns the value of the value_expression on a preceding row. Changing the offset value changes which preceding row is returned; the default value is 1, indicating the previous row in the window frame. An error occurs if offset is NULL or a negative value.

The optional default_expression is used if there isn't a row in the window frame at the specified offset. This expression must be a constant expression and its type must be implicitly coercible to the type of value_expression. If left unspecified, default_expression defaults to NULL.

To learn more about the OVER clause and how to use it, see Window function calls.

Supported Argument Types

  • value_expression can be any data type that can be returned from an expression.
  • offset must be a non-negative integer literal or parameter.
  • default_expression must be compatible with the value expression type.

Return Data Type

Same type as value_expression.

Examples

The following example illustrates a basic use of the LAG function.

WITHfinishersAS
(SELECT'Sophia Liu'asname,
TIMESTAMP'2016-10-18 2:51:45'asfinish_time,
'F30-34'asdivision
UNIONALLSELECT'Lisa Stelzner',TIMESTAMP'2016-10-18 2:54:11','F35-39'
UNIONALLSELECT'Nikki Leith',TIMESTAMP'2016-10-18 2:59:01','F30-34'
UNIONALLSELECT'Lauren Matthews',TIMESTAMP'2016-10-18 3:01:17','F35-39'
UNIONALLSELECT'Desiree Berry',TIMESTAMP'2016-10-18 3:05:42','F35-39'
UNIONALLSELECT'Suzy Slane',TIMESTAMP'2016-10-18 3:06:24','F35-39'
UNIONALLSELECT'Jen Edwards',TIMESTAMP'2016-10-18 3:06:36','F30-34'
UNIONALLSELECT'Meghan Lederer',TIMESTAMP'2016-10-18 3:07:41','F30-34'
UNIONALLSELECT'Carly Forte',TIMESTAMP'2016-10-18 3:08:58','F25-29'
UNIONALLSELECT'Lauren Reasoner',TIMESTAMP'2016-10-18 3:10:14','F30-34')
SELECTname,
finish_time,
division,
LAG(name)
OVER(PARTITIONBYdivisionORDERBYfinish_timeASC)ASpreceding_runner
FROMfinishers;
/*-----------------+-------------+----------+------------------*
 | 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 |
 *-----------------+-------------+----------+------------------*/

This next example uses the optional offset parameter.

WITHfinishersAS
(SELECT'Sophia Liu'asname,
TIMESTAMP'2016-10-18 2:51:45'asfinish_time,
'F30-34'asdivision
UNIONALLSELECT'Lisa Stelzner',TIMESTAMP'2016-10-18 2:54:11','F35-39'
UNIONALLSELECT'Nikki Leith',TIMESTAMP'2016-10-18 2:59:01','F30-34'
UNIONALLSELECT'Lauren Matthews',TIMESTAMP'2016-10-18 3:01:17','F35-39'
UNIONALLSELECT'Desiree Berry',TIMESTAMP'2016-10-18 3:05:42','F35-39'
UNIONALLSELECT'Suzy Slane',TIMESTAMP'2016-10-18 3:06:24','F35-39'
UNIONALLSELECT'Jen Edwards',TIMESTAMP'2016-10-18 3:06:36','F30-34'
UNIONALLSELECT'Meghan Lederer',TIMESTAMP'2016-10-18 3:07:41','F30-34'
UNIONALLSELECT'Carly Forte',TIMESTAMP'2016-10-18 3:08:58','F25-29'
UNIONALLSELECT'Lauren Reasoner',TIMESTAMP'2016-10-18 3:10:14','F30-34')
SELECTname,
finish_time,
division,
LAG(name,2)
OVER(PARTITIONBYdivisionORDERBYfinish_timeASC)AStwo_runners_ahead
FROMfinishers;
/*-----------------+-------------+----------+-------------------*
 | 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 |
 *-----------------+-------------+----------+-------------------*/

The following example replaces NULL values with a default value.

WITHfinishersAS
(SELECT'Sophia Liu'asname,
TIMESTAMP'2016-10-18 2:51:45'asfinish_time,
'F30-34'asdivision
UNIONALLSELECT'Lisa Stelzner',TIMESTAMP'2016-10-18 2:54:11','F35-39'
UNIONALLSELECT'Nikki Leith',TIMESTAMP'2016-10-18 2:59:01','F30-34'
UNIONALLSELECT'Lauren Matthews',TIMESTAMP'2016-10-18 3:01:17','F35-39'
UNIONALLSELECT'Desiree Berry',TIMESTAMP'2016-10-18 3:05:42','F35-39'
UNIONALLSELECT'Suzy Slane',TIMESTAMP'2016-10-18 3:06:24','F35-39'
UNIONALLSELECT'Jen Edwards',TIMESTAMP'2016-10-18 3:06:36','F30-34'
UNIONALLSELECT'Meghan Lederer',TIMESTAMP'2016-10-18 3:07:41','F30-34'
UNIONALLSELECT'Carly Forte',TIMESTAMP'2016-10-18 3:08:58','F25-29'
UNIONALLSELECT'Lauren Reasoner',TIMESTAMP'2016-10-18 3:10:14','F30-34')
SELECTname,
finish_time,
division,
LAG(name,2,'Nobody')
OVER(PARTITIONBYdivisionORDERBYfinish_timeASC)AStwo_runners_ahead
FROMfinishers;
/*-----------------+-------------+----------+-------------------*
 | 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 |
 *-----------------+-------------+----------+-------------------*/

LAST_VALUE

LAST_VALUE(value_expression[{RESPECT|IGNORE}NULLS])
OVERover_clause
over_clause:
{named_window|([window_specification])}
window_specification:
[named_window]
[PARTITIONBYpartition_expression[,...]]
ORDERBYexpression[{ASC|DESC}][,...]
[window_frame_clause]

Description

Returns the value of the value_expression for the last row in the current window frame.

This function includes NULL values in the calculation unless IGNORE NULLS is present. If IGNORE NULLS is present, the function excludes NULL values from the calculation.

To learn more about the OVER clause and how to use it, see Window function calls.

Supported Argument Types

value_expression can be any data type that an expression can return.

Return Data Type

Same type as value_expression.

Examples

The following example computes the slowest time for each division.

WITHfinishersAS
(SELECT'Sophia Liu'asname,
TIMESTAMP'2016-10-18 2:51:45'asfinish_time,
'F30-34'asdivision
UNIONALLSELECT'Lisa Stelzner',TIMESTAMP'2016-10-18 2:54:11','F35-39'
UNIONALLSELECT'Nikki Leith',TIMESTAMP'2016-10-18 2:59:01','F30-34'
UNIONALLSELECT'Lauren Matthews',TIMESTAMP'2016-10-18 3:01:17','F35-39'
UNIONALLSELECT'Desiree Berry',TIMESTAMP'2016-10-18 3:05:42','F35-39'
UNIONALLSELECT'Suzy Slane',TIMESTAMP'2016-10-18 3:06:24','F35-39'
UNIONALLSELECT'Jen Edwards',TIMESTAMP'2016-10-18 3:06:36','F30-34'
UNIONALLSELECT'Meghan Lederer',TIMESTAMP'2016-10-18 3:07:41','F30-34'
UNIONALLSELECT'Carly Forte',TIMESTAMP'2016-10-18 3:08:58','F25-29'
UNIONALLSELECT'Lauren Reasoner',TIMESTAMP'2016-10-18 3:10:14','F30-34')
SELECTname,
FORMAT_TIMESTAMP('%X',finish_time)ASfinish_time,
division,
FORMAT_TIMESTAMP('%X',slowest_time)ASslowest_time,
TIMESTAMP_DIFF(slowest_time,finish_time,SECOND)ASdelta_in_seconds
FROM(
SELECTname,
finish_time,
division,
LAST_VALUE(finish_time)
OVER(PARTITIONBYdivisionORDERBYfinish_timeASC
ROWSBETWEENUNBOUNDEDPRECEDINGANDUNBOUNDEDFOLLOWING)ASslowest_time
FROMfinishers);
/*-----------------+-------------+----------+--------------+------------------*
 | 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 |
 *-----------------+-------------+----------+--------------+------------------*/

LEAD

LEAD(value_expression[,offset[,default_expression]])
OVERover_clause
over_clause:
{named_window|([window_specification])}
window_specification:
[named_window]
[PARTITIONBYpartition_expression[,...]]
ORDERBYexpression[{ASC|DESC}][,...]

Description

Returns the value of the value_expression on a subsequent row. Changing the offset value changes which subsequent row is returned; the default value is 1, indicating the next row in the window frame. An error occurs if offset is NULL or a negative value.

The optional default_expression is used if there isn't a row in the window frame at the specified offset. This expression must be a constant expression and its type must be implicitly coercible to the type of value_expression. If left unspecified, default_expression defaults to NULL.

To learn more about the OVER clause and how to use it, see Window function calls.

Supported Argument Types

  • value_expression can be any data type that can be returned from an expression.
  • offset must be a non-negative integer literal or parameter.
  • default_expression must be compatible with the value expression type.

Return Data Type

Same type as value_expression.

Examples

The following example illustrates a basic use of the LEAD function.

WITHfinishersAS
(SELECT'Sophia Liu'asname,
TIMESTAMP'2016-10-18 2:51:45'asfinish_time,
'F30-34'asdivision
UNIONALLSELECT'Lisa Stelzner',TIMESTAMP'2016-10-18 2:54:11','F35-39'
UNIONALLSELECT'Nikki Leith',TIMESTAMP'2016-10-18 2:59:01','F30-34'
UNIONALLSELECT'Lauren Matthews',TIMESTAMP'2016-10-18 3:01:17','F35-39'
UNIONALLSELECT'Desiree Berry',TIMESTAMP'2016-10-18 3:05:42','F35-39'
UNIONALLSELECT'Suzy Slane',TIMESTAMP'2016-10-18 3:06:24','F35-39'
UNIONALLSELECT'Jen Edwards',TIMESTAMP'2016-10-18 3:06:36','F30-34'
UNIONALLSELECT'Meghan Lederer',TIMESTAMP'2016-10-18 3:07:41','F30-34'
UNIONALLSELECT'Carly Forte',TIMESTAMP'2016-10-18 3:08:58','F25-29'
UNIONALLSELECT'Lauren Reasoner',TIMESTAMP'2016-10-18 3:10:14','F30-34')
SELECTname,
finish_time,
division,
LEAD(name)
OVER(PARTITIONBYdivisionORDERBYfinish_timeASC)ASfollowed_by
FROMfinishers;
/*-----------------+-------------+----------+-----------------*
 | 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 |
 *-----------------+-------------+----------+-----------------*/

This next example uses the optional offset parameter.

WITHfinishersAS
(SELECT'Sophia Liu'asname,
TIMESTAMP'2016-10-18 2:51:45'asfinish_time,
'F30-34'asdivision
UNIONALLSELECT'Lisa Stelzner',TIMESTAMP'2016-10-18 2:54:11','F35-39'
UNIONALLSELECT'Nikki Leith',TIMESTAMP'2016-10-18 2:59:01','F30-34'
UNIONALLSELECT'Lauren Matthews',TIMESTAMP'2016-10-18 3:01:17','F35-39'
UNIONALLSELECT'Desiree Berry',TIMESTAMP'2016-10-18 3:05:42','F35-39'
UNIONALLSELECT'Suzy Slane',TIMESTAMP'2016-10-18 3:06:24','F35-39'
UNIONALLSELECT'Jen Edwards',TIMESTAMP'2016-10-18 3:06:36','F30-34'
UNIONALLSELECT'Meghan Lederer',TIMESTAMP'2016-10-18 3:07:41','F30-34'
UNIONALLSELECT'Carly Forte',TIMESTAMP'2016-10-18 3:08:58','F25-29'
UNIONALLSELECT'Lauren Reasoner',TIMESTAMP'2016-10-18 3:10:14','F30-34')
SELECTname,
finish_time,
division,
LEAD(name,2)
OVER(PARTITIONBYdivisionORDERBYfinish_timeASC)AStwo_runners_back
FROMfinishers;
/*-----------------+-------------+----------+------------------*
 | 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 |
 *-----------------+-------------+----------+------------------*/

The following example replaces NULL values with a default value.

WITHfinishersAS
(SELECT'Sophia Liu'asname,
TIMESTAMP'2016-10-18 2:51:45'asfinish_time,
'F30-34'asdivision
UNIONALLSELECT'Lisa Stelzner',TIMESTAMP'2016-10-18 2:54:11','F35-39'
UNIONALLSELECT'Nikki Leith',TIMESTAMP'2016-10-18 2:59:01','F30-34'
UNIONALLSELECT'Lauren Matthews',TIMESTAMP'2016-10-18 3:01:17','F35-39'
UNIONALLSELECT'Desiree Berry',TIMESTAMP'2016-10-18 3:05:42','F35-39'
UNIONALLSELECT'Suzy Slane',TIMESTAMP'2016-10-18 3:06:24','F35-39'
UNIONALLSELECT'Jen Edwards',TIMESTAMP'2016-10-18 3:06:36','F30-34'
UNIONALLSELECT'Meghan Lederer',TIMESTAMP'2016-10-18 3:07:41','F30-34'
UNIONALLSELECT'Carly Forte',TIMESTAMP'2016-10-18 3:08:58','F25-29'
UNIONALLSELECT'Lauren Reasoner',TIMESTAMP'2016-10-18 3:10:14','F30-34')
SELECTname,
finish_time,
division,
LEAD(name,2,'Nobody')
OVER(PARTITIONBYdivisionORDERBYfinish_timeASC)AStwo_runners_back
FROMfinishers;
/*-----------------+-------------+----------+------------------*
 | 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 |
 *-----------------+-------------+----------+------------------*/

NTH_VALUE

NTH_VALUE(value_expression,constant_integer_expression[{RESPECT|IGNORE}NULLS])
OVERover_clause
over_clause:
{named_window|([window_specification])}
window_specification:
[named_window]
[PARTITIONBYpartition_expression[,...]]
ORDERBYexpression[{ASC|DESC}][,...]
[window_frame_clause]

Description

Returns the value of value_expression at the Nth row of the current window frame, where Nth is defined by constant_integer_expression. Returns NULL if there is no such row.

This function includes NULL values in the calculation unless IGNORE NULLS is present. If IGNORE NULLS is present, the function excludes NULL values from the calculation.

To learn more about the OVER clause and how to use it, see Window function calls.

Supported Argument Types

  • value_expression can be any data type that can be returned from an expression.
  • constant_integer_expression can be any constant expression that returns an integer.

Return Data Type

Same type as value_expression.

Examples

WITHfinishersAS
(SELECT'Sophia Liu'asname,
TIMESTAMP'2016-10-18 2:51:45'asfinish_time,
'F30-34'asdivision
UNIONALLSELECT'Lisa Stelzner',TIMESTAMP'2016-10-18 2:54:11','F35-39'
UNIONALLSELECT'Nikki Leith',TIMESTAMP'2016-10-18 2:59:01','F30-34'
UNIONALLSELECT'Lauren Matthews',TIMESTAMP'2016-10-18 3:01:17','F35-39'
UNIONALLSELECT'Desiree Berry',TIMESTAMP'2016-10-18 3:05:42','F35-39'
UNIONALLSELECT'Suzy Slane',TIMESTAMP'2016-10-18 3:06:24','F35-39'
UNIONALLSELECT'Jen Edwards',TIMESTAMP'2016-10-18 3:06:36','F30-34'
UNIONALLSELECT'Meghan Lederer',TIMESTAMP'2016-10-18 3:07:41','F30-34'
UNIONALLSELECT'Carly Forte',TIMESTAMP'2016-10-18 3:08:58','F25-29'
UNIONALLSELECT'Lauren Reasoner',TIMESTAMP'2016-10-18 3:10:14','F30-34')
SELECTname,
FORMAT_TIMESTAMP('%X',finish_time)ASfinish_time,
division,
FORMAT_TIMESTAMP('%X',fastest_time)ASfastest_time,
FORMAT_TIMESTAMP('%X',second_fastest)ASsecond_fastest
FROM(
SELECTname,
finish_time,
division,finishers,
FIRST_VALUE(finish_time)
OVERw1ASfastest_time,
NTH_VALUE(finish_time,2)
OVERw1assecond_fastest
FROMfinishers
WINDOWw1AS(
PARTITIONBYdivisionORDERBYfinish_timeASC
ROWSBETWEENUNBOUNDEDPRECEDINGANDUNBOUNDEDFOLLOWING));
/*-----------------+-------------+----------+--------------+----------------*
 | 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 |
 *-----------------+-------------+----------+--------------+----------------*/

PERCENTILE_CONT

PERCENTILE_CONT(value_expression,percentile[{RESPECT|IGNORE}NULLS])
OVERover_clause
over_clause:
{named_window|([window_specification])}
window_specification:
[named_window]
[PARTITIONBYpartition_expression[,...]]

Description

Computes the specified percentile value for the value_expression, with linear interpolation.

This function ignores NULL values if RESPECT NULLS is absent. If RESPECT NULLS is present:

  • Interpolation between two NULL values returns NULL.
  • Interpolation between a NULL value and a non-NULL value returns the non-NULL value.

To learn more about the OVER clause and how to use it, see Window function calls.

PERCENTILE_CONT can be used with differential privacy. To learn more, see Differentially private aggregate functions.

Supported Argument Types

  • value_expression and percentile must have one of the following types:
    • NUMERIC
    • BIGNUMERIC
    • FLOAT64
  • percentile must be a literal in the range [0, 1].

Return Data Type

The return data type is determined by the argument types with the following table.

INPUTNUMERICBIGNUMERICFLOAT64
NUMERICNUMERICBIGNUMERICFLOAT64
BIGNUMERICBIGNUMERICBIGNUMERICFLOAT64
FLOAT64FLOAT64FLOAT64FLOAT64

Examples

The following example computes the value for some percentiles from a column of values while ignoring nulls.

SELECT
PERCENTILE_CONT(x,0)OVER()ASmin,
PERCENTILE_CONT(x,0.01)OVER()ASpercentile1,
PERCENTILE_CONT(x,0.5)OVER()ASmedian,
PERCENTILE_CONT(x,0.9)OVER()ASpercentile90,
PERCENTILE_CONT(x,1)OVER()ASmax
FROMUNNEST([0,3,NULL,1,2])ASxLIMIT1;
/*-----+-------------+--------+--------------+-----*
 | min | percentile1 | median | percentile90 | max |
 +-----+-------------+--------+--------------+-----+
 | 0 | 0.03 | 1.5 | 2.7 | 3 |
 *-----+-------------+--------+--------------+-----*/

The following example computes the value for some percentiles from a column of values while respecting nulls.

SELECT
PERCENTILE_CONT(x,0RESPECTNULLS)OVER()ASmin,
PERCENTILE_CONT(x,0.01RESPECTNULLS)OVER()ASpercentile1,
PERCENTILE_CONT(x,0.5RESPECTNULLS)OVER()ASmedian,
PERCENTILE_CONT(x,0.9RESPECTNULLS)OVER()ASpercentile90,
PERCENTILE_CONT(x,1RESPECTNULLS)OVER()ASmax
FROMUNNEST([0,3,NULL,1,2])ASxLIMIT1;
/*------+-------------+--------+--------------+-----*
 | min | percentile1 | median | percentile90 | max |
 +------+-------------+--------+--------------+-----+
 | NULL | 0 | 1 | 2.6 | 3 |
 *------+-------------+--------+--------------+-----*/

PERCENTILE_DISC

PERCENTILE_DISC(value_expression,percentile[{RESPECT|IGNORE}NULLS])
OVERover_clause
over_clause:
{named_window|([window_specification])}
window_specification:
[named_window]
[PARTITIONBYpartition_expression[,...]]

Description

Computes the specified percentile value for a discrete value_expression. The returned value is the first sorted value of value_expression with cumulative distribution greater than or equal to the given percentile value.

This function ignores NULL values unless RESPECT NULLS is present.

To learn more about the OVER clause and how to use it, see Window function calls.

Supported Argument Types

  • value_expression can be any orderable type.
  • percentile must be a literal in the range [0, 1], with one of the following types:
    • NUMERIC
    • BIGNUMERIC
    • FLOAT64

Return Data Type

Same type as value_expression.

Examples

The following example computes the value for some percentiles from a column of values while ignoring nulls.

SELECT
x,
PERCENTILE_DISC(x,0)OVER()ASmin,
PERCENTILE_DISC(x,0.5)OVER()ASmedian,
PERCENTILE_DISC(x,1)OVER()ASmax
FROMUNNEST(['c',NULL,'b','a'])ASx;
/*------+-----+--------+-----*
 | x | min | median | max |
 +------+-----+--------+-----+
 | c | a | b | c |
 | NULL | a | b | c |
 | b | a | b | c |
 | a | a | b | c |
 *------+-----+--------+-----*/

The following example computes the value for some percentiles from a column of values while respecting nulls.

SELECT
x,
PERCENTILE_DISC(x,0RESPECTNULLS)OVER()ASmin,
PERCENTILE_DISC(x,0.5RESPECTNULLS)OVER()ASmedian,
PERCENTILE_DISC(x,1RESPECTNULLS)OVER()ASmax
FROMUNNEST(['c',NULL,'b','a'])ASx;
/*------+------+--------+-----*
 | x | min | median | max |
 +------+------+--------+-----+
 | c | NULL | a | c |
 | NULL | NULL | a | c |
 | b | NULL | a | c |
 | a | NULL | a | c |
 *------+------+--------+-----*/

Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.

Last updated 2025年10月24日 UTC.