Operator GenericFeatureConstruction

This operator creates an output attribute on the basis of a given SQL definition (Parameter SQL_String). The definition must be well-formed SQL defining how values for the output attribute are computed based on one of the attributes in TheInputConcept. To refer to the attributes in TheInputConcept, the names of the `BaseAttribute`s are used--and not the names of any `Column`s. For example, if there are two `BaseAttribute`s named "INCOME" and "TAX" in TheInputConcept, this operator can compute their sum if SQL_String is defined as "(INCOME + TAX)". Since the operator must resolve names of `BaseAttribute`s, it cannot be used if there are two or more `BaseAttribute`s in TheInputConcept with the same name.

TheTargetAttribute is needed to have a blueprint for TheOutputAttribute. The operator ignores TheTargetAttribute, except that it uses the relational datatype of its column to specify the relational datatype for the column of TheOutputAttribute.

### Parameter

Parameter | Object | Type | optional | min_arg | max_arg | looped | Remarks
TheInputConcept | Concept | Input | no | 1 | 1 | no | inherited
TheTargetAttribute | BaseAttribute | Input | no | 1 | 1 | yes | inherited; specifies datatype
SQL_String | Value | Input | no | 1 | 1 | yes | see text
TheOutputAttribute | BaseAttribute | Output | no | 1 | 1 | yes | inherited

The Operator GenericFeatureConstruction is loopable!