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Oracle® OLAP Reference 10g Release 2 (10.2) Part Number B14350-01 |
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# OLAP_EXPRESSION Overview

`OLAP_EXPRESSION` acts as a numeric single-row function within the context of a `SELECT FROM OLAP_TABLE` statement. You can specify `OLAP_EXPRESSION` in the same way you specify other Oracle single-row functions, notably in the select list, `WHERE` , and `ORDER BY` clauses.

## Single-Row Functions

Single-row functions return a single result row for every row of a queried table or view. Oracle supports a number of predefined single-row functions, for example `COS`, `LOG`, and `ROUND` which return numeric data, and `UPPER` and `LOWER` which return character data. For more information on single-row functions, refer to the Oracle Database SQL Reference.

The OLAP single-row functions, `OLAP_EXPRESSION` and its variants for text, date, and boolean data, return the result of an OLAP DML expression that you specify. The OLAP DML supports a rich syntax for specifying computations ranging from simple arithmetic expressions to statistical, financial, and time-series operations. You can use `OLAP_EXPRESSION` to dynamically perform any valid numeric expression within an analytic workspace and retrieve its results. For more information on OLAP DML expressions, refer to the Oracle OLAP DML Reference.

## OLAP_EXPRESSION and OLAP_TABLE

`OLAP_TABLE` uses a limit map to present the multidimensional data from an analytic workspace in tabular form. The limit map specifies the columns of the logical table. When an `OLAP_EXPRESSION` function is specified in the select list of the query, `OLAP_TABLE` generates additional columns for the results of the function.

To use `OLAP_EXPRESSION`, you must specify a `ROW2CELL` clause in the limit map used by `OLAP_TABLE`. `ROW2CELL` identifies a `RAW` column that `OLAP_TABLE` populates with information used by the OLAP single-row functions.

See Also: "Limit Maps" and "Limit Map: ROW2CELL Clause"