Database modeling
The Omnis Studio schema clesses define the structure of the database tables.
In addition to the Omnis Studio properties for the schema columns:
Crossmodel includes an ample set of properties that can create and maintainthe database in a more advanced way.
CrossModel can create and maintain database views, that can be used for different purposes:
The views can be read write, even if thay include multiple tables (complex views)
Mirror views create aliases of a table-view with an optional extension applied to all the columns.
The aliases can be used in different situations. One of the most common is whan a record needs to be connected to more that one record of the same table.
The selection views apply a WHERE clause to the table, with an automatic filter on the records.
In the manual views, the SELECT statement is created by the developer, and can be in any form.
The statement is anyway included in a schema, that once created can have the same properties of a table schema, including connections, and can be used in any part of the program in the same way.
This kind of view can be used in many cases, for example to show a record twice.
The complex views are one of the most powerful features of CrossModel.
These views include two or more different table or views, and still they can be inserted or updated like a single table, thanks to the insert-update stored procedures.
One of the most important features to meet tha ACID requirements of modern database is the possibility to create connections between tables with foreign keys, to ensure data integrity.
CrossModel can create and mantain connections between schemas (tables of the database), allowing full use of referential integrity of the databases.