5.6.2 Adding a Layer of Points

Consider a map layer that shows each employee's home address as a point by joining EMP with a separate EMP_ADDRESSES table. You can configure a single data source at the map region level, then reference it in the layers. Or each layer can define its own data source.

To simplify maintenance, consider creating a database view to encapsulate the region's SQL query. Then use it as the region's data source and pick column names to use in the layer. For example, consider the following EMP_WITH_ADDRESSES view that joins EMP and EMP_ADDRESSES and includes a computed TOTAL_COMPENSATION column:

create or replace view emp_with_addresses as 
select e.empno,
       e.ename,
       a.address,
       a.latitude,
       a.longitude,
       e.sal + nvl(e.comm,0) as total_compensation
  from emp e
  join emp_addresses a 
    on a.empno = e.empno;

Then the map uses this view, configures its points using the LATITUDE and LONGITUDE columns, and defines the tooltip using the HTML Expression:

&ENAME. - &ADDRESS.

The figure below shows the resulting map, with its single point layer showing employee addresses around San Francisco, California and Marin County. Notice the user is hovering the mouse over BLAKE's point marker, and the tooltip displays "BLAKE - 1246 Palou Ave, San Francisco, CA 94124".

Figure 5-12 Maps Showing Employees Addresses

Description of "Figure 5-12 Maps Showing Employees Addresses"