mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-17 03:42:48 +00:00
79 lines
2.7 KiB
Markdown
79 lines
2.7 KiB
Markdown
---
|
||
slug: /en/sql-reference/window-functions/first_value
|
||
sidebar_label: first_value
|
||
sidebar_position: 3
|
||
---
|
||
|
||
# first_value
|
||
|
||
Returns the first value evaluated within its ordered frame. By default, NULL arguments are skipped, however the `RESPECT NULLS` modifier can be used to override this behaviour.
|
||
|
||
**Syntax**
|
||
|
||
```sql
|
||
first_value (column_name) [[RESPECT NULLS] | [IGNORE NULLS]]
|
||
OVER ([[PARTITION BY grouping_column] [ORDER BY sorting_column]
|
||
[ROWS or RANGE expression_to_bound_rows_withing_the_group]] | [window_name])
|
||
FROM table_name
|
||
WINDOW window_name as ([[PARTITION BY grouping_column] [ORDER BY sorting_column])
|
||
```
|
||
|
||
Alias: `any`.
|
||
|
||
:::note
|
||
Using the optional modifier `RESPECT NULLS` after `first_value(column_name)` will ensure that `NULL` arguments are not skipped.
|
||
See [NULL processing](../aggregate-functions/index.md/#null-processing) for more information.
|
||
:::
|
||
|
||
For more detail on window function syntax see: [Window Functions - Syntax](./index.md/#syntax).
|
||
|
||
**Returned value**
|
||
|
||
- The first value evaluated within its ordered frame.
|
||
|
||
**Example**
|
||
|
||
In this example the `first_value` function is used to find the highest paid footballer from a fictional dataset of salaries of Premier League football players.
|
||
|
||
Query:
|
||
|
||
```sql
|
||
DROP TABLE IF EXISTS salaries;
|
||
CREATE TABLE salaries
|
||
(
|
||
`team` String,
|
||
`player` String,
|
||
`salary` UInt32,
|
||
`position` String
|
||
)
|
||
Engine = Memory;
|
||
|
||
INSERT INTO salaries FORMAT Values
|
||
('Port Elizabeth Barbarians', 'Gary Chen', 196000, 'F'),
|
||
('New Coreystad Archdukes', 'Charles Juarez', 190000, 'F'),
|
||
('Port Elizabeth Barbarians', 'Michael Stanley', 100000, 'D'),
|
||
('New Coreystad Archdukes', 'Scott Harrison', 180000, 'D'),
|
||
('Port Elizabeth Barbarians', 'Robert George', 195000, 'M'),
|
||
('South Hampton Seagulls', 'Douglas Benson', 150000, 'M'),
|
||
('South Hampton Seagulls', 'James Henderson', 140000, 'M');
|
||
```
|
||
|
||
```sql
|
||
SELECT player, salary,
|
||
first_value(player) OVER (ORDER BY salary DESC) AS highest_paid_player
|
||
FROM salaries;
|
||
```
|
||
|
||
Result:
|
||
|
||
```response
|
||
┌─player──────────┬─salary─┬─highest_paid_player─â”<C3A2>
|
||
1. │ Gary Chen │ 196000 │ Gary Chen │
|
||
2. │ Robert George │ 195000 │ Gary Chen │
|
||
3. │ Charles Juarez │ 190000 │ Gary Chen │
|
||
4. │ Scott Harrison │ 180000 │ Gary Chen │
|
||
5. │ Douglas Benson │ 150000 │ Gary Chen │
|
||
6. │ James Henderson │ 140000 │ Gary Chen │
|
||
7. │ Michael Stanley │ 100000 │ Gary Chen │
|
||
└─────────────────┴────────┴─────────────────────┘
|
||
``` |