Computed columns in
a table contain data values that are derived from other columns in
the table. Staged tables contain computed columns for data that is
not directly provided by the raw data source. Instead, the computed
columns might be useful for reporting or promoting consistency across
various data sources. For example, a data source normally has a datetime
stamp and from that datetime stamp, SAS IT Resource Management might
provide a computed column that calculates weeks or months.
Note: A computed column should
not be used as a source of calculations for other computed columns.
Using a computed column as a source for a computation can be problematic
because the order of computing the values for the computed column
is not guaranteed.
To find a computed column
in a staged table and view the formula that it uses, right-click the
staged table in a process flow diagram and select
Properties.
Then, open the
Columns tab of the staged
table's
Properties dialog box. This method
is the only way to view the
Expression column.
Note: If you open a table from
a folder view or from the IT Data Marts view, and select the
Columns tab,
the columns of the table are displayed. However, the expressions that
are associated with the columns are not displayed.
All computed columns
contain a formula or expression in the
Expression column
of the grid.
Note: You can use a SAS macro in
a formula expression or in the expression for a computed column.
The SAS macro definition needs to be available to the SAS session
that executes the staging or aggregation job that populates the computed
column. For example, you might need to add a new autocall library
using the SASAUTOS SAS option in the SAS configuration.
You can double-click
an expression to modify it for the column. To open the Expression
Builder, click the ellipsis button in the cell. For information about
how to work with the Expression Builder, click
Help in
the
Expression Builder window.
Note: Aggregation tables also use computed columns. You can
use the computed columns that are provided for these tables and you
can create your own.
For more information about creating and using computed columns,
see Specify Computed Columns.