Defining Physical to Logical Table Source Mappings

Use the Column Mapping tab of the Logical Table Source dialog box to map logical columns to physical columns. The physical to logical mapping can also be used to specify transformations that occur between the Physical layer and the Business Model and Mapping layer. The transformations can be simple, such as changing an integer data type to a character, or more complex, such as applying a formula to find a percentage of sales per unit of population.

To map logical columns to physical columns

1. In the Business Model and Mapping layer, double-click a logical table source, if the Logical Table Source dialog box is not already open.
2. In the Logical Table Source dialog box, click the Column Mapping tab.
3. In the Column Mapping tab, maximize or enlarge the dialog box to show all the contents, as shown in Figure 11.
   NOTE:  In the Column Mapping tab, in the Logical column to physical column area, you can sort the rows (toggle among ascending order, descending order, and then restore original order) by clicking a column heading.
4. In the Physical Table column, select the table that contains the column you want to map.
   When you select a cell in the Physical Table column, a drop-down list appears. It contains a list of tables currently included in this logical table source.
5. In the Expression list, select the physical column corresponding to each logical column.
   When you select a cell in the Expression column, a drop-down list appears. It contains a list of tables currently included in this logical table source.
6. To open the Expression Builder, click the ellipsis button to the left of the Expression you want to view or edit.
   NOTE:  All columns used in creating physical expressions must be in tables included in the logical table source. You cannot create expressions involving columns in tables outside the source.
7. To remove a column mapping, click the delete button.
   You might need to scroll to the right to locate the delete button.
8. After you map the appropriate columns, click OK.

Figure 11. Logical Table Source Dialog Box

To remove a column mapping

1. In the Business Model and Mapping layer, right-click a logical table and choose New Object > Logical Table Source.
2. In the Logical Table Source dialog box, click the Column Mapping tab.
3. In the Column Mapping tab, maximize or enlarge the dialog box to show all the contents, as shown in Figure 11.
4. To remove a column mapping, click the delete button next to the Physical Table cell.
5. Click OK.

Unmapping a Logical Column from Its Source

In the Logical Column dialog box, the Datatype tab contains information about the logical column. You can edit the logical table sources from which the column derives its data, or unmap it from its sources.

To unmap a logical column from its source

1. In the Business Model and Mapping layer, double-click a logical column.
2. In the Logical Column dialog box, click the Datatype tab.
3. In the Datatype tab, in the Logical Table Source list, select a source and click Unmap.
4. Click OK.