Categories: Window

FIRST_VALUE

Returns the first value within an ordered group of a result set.

Syntax

FIRST_VALUE(expression) OVER ( [PARTITION BY partition_expression] [ORDER BY order_expression] [ (ASC | DESC) ] ) → same as input type

• expression: The expression that determines the return value.
• partition_expression (optional): An optional expression that groups rows into partitions. You can specify a single expression or a comma-separated list of expressions. For example, PARTITION BY column1, column3, …
• order_expression: An expression that specifies the order of the rows within each partition. You can specify a single expression or a comma-separated list of expressions. For example, PARTITION BY column1, column3, …

Examples

SELECT city, state, pop, 
FIRST_VALUE(pop) OVER (PARTITION BY state ORDER BY city)
FROM Samples."samples.dremio.com"."zips.json"

-- city, state, pop, EXPR$3
-- 98791, AK, 5345, 5345
-- AKHIOK, AK, 13309, 5345
-- AKIACHAK, AK, 481, 5345
-- ...