PREV()

Other. Returns the value of a given column from a prior row.

Syntax

PREV( column [, offset]) GETTIMESTAMP(PREV( name ))

Parameters
column	The name of a column of any type.
offset	Which row to use, with 0 as the current row, 1 as the immediately previous row, and so on. If omitted, defaults to1.
name	The name of a stream or window.

Data Types
Return	column	offset
The same type as the specified column.	String	Integer

Return	name
Timestamp	String

When you use PREV() on a data source grouped with GROUP BY or PER, offset refers to a previous row within the same group as the newly arrived row.

PREV embedded in GETTIMESTAMP returns the timestamp of the previous row in the specified stream or window.

You can use PREV() in a WHERE selection condition or a SELECT clause select list.

When you use PREV() on data streams, it is semantically identical to the [ ] row operator.

The following example returns the value of the Price column from the row two previous to the current row:

INSERT INTO OutStream
SELECT PREV(Trades.Price, 2)
FROM Trades;