SQL Functions, Operators, Expressions, and Predicates > Ordered Analytical Functions
  
Ordered Analytical Functions
This chapter describes ordered analytical functions that enable and expedite the processing of queries containing On Line Analytical Processing (OLAP) style decision support requests.
Ordered analytical functions include ANSI SQL:2008 compliant window functions, as well as Teradata SQL-specific functions.
Ordered Analytical Functions
Ordered analytical functions provide support for many common operations in analytical processing and data mining environments that require an ordered set of results rows or depend on values in a previous row.
For example, computing a seven-day running sum requires:
First, that rows be ordered by date.
Then, the value for the running sum must be computed,
Adding the current row value to the value of the sum from the previous row, and
Subtracting the value from the row eight days ago.