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Oracle® OLAP DML Reference 10g Release 2 (10.2) Part Number B14346-01 |
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# 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 Using a Forecast Context".

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

Example 12-9 A Forecasting Program

Suppose you define a program named `autofcst` to perform a forecast from the data that is in an input variable named `fcin1`. The `fcin1` variable is dimensioned by a time dimension named `timedim`. Assume that you have defined a program named `autofcst` with the following definition and specification.

    DEFINE autofcst PROGRAM
    PROGRAM
    " Using the Automatic forecasting method
    " Suppose you want to create a forecast from the data in
    " an input variable named fcin1 that is dimensionsed by
    " a time dimension named timedim.
    "
    " Open a forecasting context
    hndl = FCOPEN('MyForecast')
    " Initialize the target variables
    fcout1 = NA
    fcseas1 = NA
    fcsmseas1 = NA
    " Specify that the forecast be of the AUTOMATIC type
    fcset hndl method 'automatic'
    " Execute the forecast
    FCEXEC hndl time timedim INTO fcout1 -
          seasonal fcseas1 smseasonal fcsmseas1 backcast fcin1
    " Create a report showing the input and output of the forecast
    REPORT DOWN timedim fcin1 fcout1 fcseas1 fcsmseas1
    " Run a program named queryall to retrieve the characteristics
    " of the forecasting trials
    QUERYALL
    " Close the forecasting context
    FCCLOSE hndl
    END

The `autofcst` program opens a forecasting context, sets the option of the forecast to AUTOMATIC, reports on the forecasted data, and queries and reports the characteristics of the various trials that Oracle OLAP performed to determine the method to use, and closes the forecasting context.

The `autofcst` program contains the following report command that displays a report of the input to and the output from the forecast.

    REPORT DOWN timedim fcin1 fcout1 fcseas1 fcsmseas1

The sample report created by this statement follows.

    TIMEDIM          FCIN1      FCOUT1    FCSEAS1   FCSMSEAS1
    -------------- ---------- ---------- ---------- ----------
    Jan97                  NA         NA 1.06725482 1.02926773
    Feb97                  NA         NA .978607917 .945762221
    Mar97                  NA         NA 1.12699278 .860505188
    Apr97                  NA         NA .576219022 .905284834
    May97                  NA         NA .920601317 .907019312
    Jun97                  NA         NA 0.91118344  1.0580697
    Jul97                  NA         NA 1.07886483 1.05597234
    Aug97                  NA         NA 1.08101034   1.054612
    Sep97                  NA         NA 1.08077427 1.05361672
    Oct97               2,914         NA 1.08351799 1.05380407
    Nov97               2,500         NA 1.01126778 1.04504316
    Dec97               2,504         NA 1.08370549 1.03104272
    Jan98               3,333         NA         NA         NA
    Feb98               2,512         NA         NA         NA
    Mar98               2,888         NA         NA         NA
    ...                 ...           ...        ...        ...
    Jan01                  NA 3,371.7631         NA         NA
    Feb01                  NA 2,736.4811         NA         NA
    Mar01                  NA 3,408.3656         NA         NA
    Apr01                  NA 714.277175         NA         NA
    May01                  NA 2,502.9315         NA         NA
    Jun01                  NA 3,195.3626         NA         NA
    Jul01                  NA 3,911.6058         NA         NA
    Aug01                  NA  4,000.651         NA         NA
    Sep01                  NA 4,220.2658         NA         NA
    Oct01                  NA 3,416.0208         NA         NA
    Nov01                  NA 2,827.3943         NA         NA
    Dec01                  NA 2,990.8629         NA         NA

The `queryall` program and a sample report created from its output is shown in "Querying a Forecast".