lead
返回一个值,该值在有序框架内的当前行之后偏移行的行中进行评估。
此函数类似于 leadInFrame
,但总是使用 ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
框架。
语法
lead(x[, offset[, default]])
OVER ([[PARTITION BY grouping_column] [ORDER BY sorting_column]] | [window_name])
FROM table_name
WINDOW window_name as ([[PARTITION BY grouping_column] [ORDER BY sorting_column])
有关窗口函数语法的更多详细信息,请参见:窗口函数 - 语法。
参数
x
— 列名称。offset
— 要应用的偏移量。 (U)Int*。 (可选 - 默认值为1
)。default
— 如果计算的行超出窗口框架的边界要返回的值。 (可选 - 省略时使用列类型的默认值)。
返回值
- 在有序框架内的当前行之后偏移行的行中评估的值。
示例
此示例查看诺贝尔奖获奖者的 历史数据,并使用 lead
函数返回物理类别的连续获奖者列表。
CREATE OR REPLACE VIEW nobel_prize_laureates
AS SELECT *
FROM file('nobel_laureates_data.csv');
SELECT
fullName,
lead(year, 1, year) OVER (PARTITION BY category ORDER BY year ASC
ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
) AS year,
category,
motivation
FROM nobel_prize_laureates
WHERE category = 'physics'
ORDER BY year DESC
LIMIT 9
┌─fullName─────────┬─year─┬─category─┬─motivation─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
1. │ Anne L Huillier │ 2023 │ physics │ for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter │
2. │ Pierre Agostini │ 2023 │ physics │ for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter │
3. │ Ferenc Krausz │ 2023 │ physics │ for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter │
4. │ Alain Aspect │ 2022 │ physics │ for experiments with entangled photons establishing the violation of Bell inequalities and pioneering quantum information science │
5. │ Anton Zeilinger │ 2022 │ physics │ for experiments with entangled photons establishing the violation of Bell inequalities and pioneering quantum information science │
6. │ John Clauser │ 2022 │ physics │ for experiments with entangled photons establishing the violation of Bell inequalities and pioneering quantum information science │
7. │ Giorgio Parisi │ 2021 │ physics │ for the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales │
8. │ Klaus Hasselmann │ 2021 │ physics │ for the physical modelling of Earths climate quantifying variability and reliably predicting global warming │
9. │ Syukuro Manabe │ 2021 │ physics │ for the physical modelling of Earths climate quantifying variability and reliably predicting global warming │
└──────────────────┴──────┴──────────┴────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘