The Expression Fields extension extends
geodatabase functionality to support auto-calculations
of record values based
on triggered changes and calculation expressions.
An expression field is one whose value is always
derived from other database values, whether on the
same row or related rows defined by the relational
database. The expression that determines the result
value is written using VBScript syntax.
Single Row Expression
A Single Row Expression is appropriate when all the
necessary data for an Expression Field exists on
the same record to which the Expression Field applies.
Relationship Row Expression
Sometimes it is convenient for the design of a database
to have closely related information split into separate
fields as well as across multiple tables. Often,
this closely related information needs to be gathered
and displayed in one place. Relationship Row Expressions
were created specifically to facilitate bringing
these various pieces of data together as well as
help eliminate redundant data entry. Relationship
Row Expressions allow the database administrator
to create a series of expressions that extract values
from a set of related tables and then make a composite
expression that defines a result value from the extracted
values.
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