LAG/LEAD Function | Teradata Vantage - 17.10 - LAG/LEAD - Advanced SQL Engine - Teradata Database

Teradata Vantageā„¢ - SQL Functions, Expressions, and Predicates

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1145-171K
Language
English (United States)

Ordered analytic functions calculate an aggregate or non-aggregate value on a window of rows within a group of rows. The window of rows is defined by the Window Framing clause, also called the ROWS clause. Window sizes are based on the size specified in the ROWS clause. The group of rows is defined by the PARTITION BY clause of the Window function.

The LAG function accesses data from the row preceding the current row at a specified offset value in a window group, while the LEAD function returns data from the row following the current row. If the offset value is outside the scope of the window, the user-specified default value is returned.

The LAG and LEAD functions are used for OLAP and decision support queries.