Book Image

Applying and Extending Oracle Spatial

By : Siva Ravada, Simon Greener
Book Image

Applying and Extending Oracle Spatial

By: Siva Ravada, Simon Greener

Overview of this book

Spatial applications should be developed in the same way that users develop other database applications: by starting with an integrated data model in which the SDO_GEOMETRY objects are just another attribute describing entities and by using as many of the database features as possible for managing the data. If a task can be done using a database feature like replication, then it should be done using the standard replication technology instead of inventing a new procedure for replicating spatial data. Sometimes solving a business problem using a PL/SQL function can be more powerful, accessible, and easier to use than trying to use external software. Because Oracle Spatial's offerings are standards compliant, this book shows you how Oracle Spatial technology can be used to build cross-vendor database solutions. Applying and Extending Oracle Spatial shows you the clever things that can be done not just with Oracle Spatial on its own, but in combination with other database technologies. This is a great resource book that will convince you to purchase other Oracle technology books on non-spatial specialist technologies because you will finally see that "spatial is not special: it is a small, fun, and clever part of a much larger whole".
Table of Contents (20 chapters)
Applying and Extending Oracle Spatial
About the Authors
About the Reviewers
Table Comparing Simple Feature Access/SQL and SQL/MM–Spatial

Using row-level and statement-level triggers

Database triggers can be defined as row-level or statement-level triggers. All the triggers we have seen so far in Chapter 1, Defining a Data Model for Spatial Data Storage, are defined as row-level triggers; that means the trigger is executed for each row of the table that is inserted, deleted, or updated. In some cases, we do not want the trigger to execute for each row, but we want it to execute for the whole SQL statement. For example, consider the following two SQL statements:

Insert Into LAND_PARCELS Values(3326028, '0026T05AA', '0026T', '055A',
 '2655',   'HYDE', '1 ST', 'HYDE', 'ST',  'O',
SDO_GEOMETRY(2003, 2872, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARRAY(6006801.83, 2121396.9,  6006890.33, 2121409.23,  6006878.19, 2121495.89,  6006788.97, 2121483.45 )), NULL);


Let's assume that the TEMP_LAND_PARCELS table has ten rows. The first statement inserts one row into the...