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Version: current [24.2.x]

LEAD

Categories: Window

LEAD

Returns the row after the current one in the same result set without the need for a self-join. If there are no rows, this function returns NULL.

Syntax​

LEAD(expression, [offset]) OVER ([PARTITION BY partition_expression][ORDER BY order_expression]) → same as input type​

  • expression (optional): An expression that is returned.
  • offset (optional): The number of rows after the current row from which to obtain a value. Supports only a value of 1.
  • partition_expression (optional): An optional expression that groups rows into partitions.
  • order_expression: An optional expression that specifies the order of the rows within each partition.

Examples

LEAD example
SELECT "Category", 
  "Descript", 
  "DayOfWeek",
  LEAD(DayOfWeek, 1) 
    OVER (
      PARTITION BY "Category" 
      ORDER BY "DayOfWeek")
FROM Samples."samples.dremio.com"."SF_incidents2016.json"
-- Category, Descript, DayOfWeek, EXPR$3
-- ARSON, ARSON, Friday, Friday 
-- ARSON, ARSON OF A VEHICLE, Wednesday, null