prev()

Returns the value of a specific column in a specified row. The specified row is at a specified offset from the current row in a serialized row set.

Syntax

There are several possibilities.

  • prev(column)

  • prev(column, offset)

  • prev(column, offset, default_value)

Arguments

  • column: The column to get the values from.

  • offset: The offset to go back in rows. When no offset is specified, a default offset 1 is used.

  • default_value: The default value to be used when there are no previous rows to take the value from. When no default value is specified, null is used.

Examples

Table | serialize | extend prevA = prev(A,1)
| extend diff = A - prevA
| where diff > 1

Table | serialize prevA = prev(A,1,10)
| extend diff = A - prevA
| where diff <= 10