FCEXEC

The FCEXEC command executes a forecast based on the parameters options specified by the FCSET command for the forecast. The FCEXEC command implicitly loops over all the dimensions of the expression other than the time dimension.

You must use the FCEXEC command in combination with other OLAP DML statements as outlined in "Forecasting Programs". For additional information about forecasting and forecasting methods, we suggest the latest editions of the books listed in "Further Reading on Forecasting".

Syntax

FCEXEC handle-expression [choice] time-series-expression

where:

choice is one or more of the following:

     TIME time-dimension

     TRADINGDAYS expression

     INTO name

     SEASONAL name

     SMSEASONAL name

     BACKCAST

Arguments

handle-expression

An INTEGER expression that specifies the handle to a forecasting context previously opened using the FCOPEN function.

TIME time-dimension

The name of the time dimension. You do not have to specify this parameter when one dimension of the time-series-expression is of type DAY, WEEK, MONTH, QUARTER, or YEAR.

TRADINGDAYS expression

An INTEGER expression that specifies the number of business days in the unit of time of the time data type (that is, DAY, WEEK, MONTH, or YEAR) of the time-series-expression. By default the value is the total number of days in the unit of time.

INTO name

The name of the Oracle OLAP variable in which Oracle OLAP stores the forecast data. This variable must be dimensioned by the time dimension and any other dimensions of the time-series-expression that have more than one value in status. (This variable can have additional dimensions. However, in this case, when Oracle OLAP executes the forecast, it limits each of these additional dimensions to the first value in the dimension's status list.).

Important: When you do not specify INTO and the time-series-expression names an Oracle OLAP variable, Oracle OLAP populates the input variable with the output data of the forecast, thus overwriting the original data.

SEASONAL name

The name of the variable that Oracle OLAP populates with the data that represents seasonal factors. Oracle OLAP produces only one cycle of factors and stores these values into this variable beginning with the first time period in status. This variable must be dimensioned by the time dimension and any other dimensions of the time-series-expression that have more than one value in status. (This variable can have additional dimensions. However, in this case, when Oracle OLAP executes the forecast, it limits each of these additional dimensions to the first value in the dimension's status list.)

SMSEASONAL name

The name of the variable that Oracle OLAP populates with the data that represents smoothed seasonal factors. Oracle OLAP produces only one cycle of factors and stores these values into this variable beginning with the first time period in status; all other values are set to NA. This variable must be dimensioned by the time dimension and any other dimensions of the time-series-expression that have more than one value in status. (This variable can have additional dimensions. However, in this case, when Oracle OLAP executes the forecast, it limits each of these additional dimensions to the first value in the dimension's status list.)

BACKCAST

The BACKCAST keyword specifies that Oracle OLAP returns fitted historical data. Typically this data is available only for a subset of the historical periods (sometimes called the "fit window"). Oracle OLAP sets the value of the data that corresponds to the historical time periods that are outside of the fit window to NA.

Important: When you specify a value for BACKCAST and do not specify a value for INTO variable, Oracle OLAP populates the source variable with the backcasted data, thus overwriting the original data.

time-series-expression

An expression that specifies the data from which FCEXEC calculates values. The time-series-expression must be a numeric expression that is dimensioned by time-dimension. The time-series-expression may also be dimensioned by other dimensions. In this case, FCEXEC implicitly loops over all the dimensions of the expression other than the time dimension. The maximum status length of the time-series-expression is 5000.

Notes

Forecasting a Single Value

The FCEXEC command implicitly loops over all the dimensions of the time-series expression other than the time dimension. When you want to forecast only one value of a multidimensional time-series expression, then you must limit the status of all non-time dimensions to a single value before you execute the FCEXEC command.

Examples

For a full example of a forecasting program, see Example 12-10, "A Forecasting Program"..