Introduction to the Default SQL Projection

For any persistent class, the compiler generates an SQL table definition, so that the stored data can be accessed via SQL in addition to via the object interface.

The table contains one record for each saved object, and the table can be queried via InterSystems SQL. The following shows the results of a query of the Sample.Person table:

Table showing seven rows, and columns including ID, Age, DOB, Favorite Colors, Name, SSN, Spouse, Home City, and Home State.

The following table summarizes the default projection:

The Object-SQL Projection

From (Object Concept) ...	To (Relational Concept) ...
Package	Schema
Class	Table
OID	Identity field
Data type property	Field
Reference property	Reference field
Embedded object	Set of fields
List property	List field
Array property	Child table
Stream property	BLOB
Index	Index
Class method	Stored procedure

Other topics provide details and describe any changes you can make:

For information on the table name and the name of the schema to which it belongs, see Defining Persistent Classes.
The same topic also has information on how you can control the projection of subclasses.
For information on the projection of literal properties, see Defining and Using Literal Properties.
For information on the projection of collection properties, see Storage and SQL Projection of Collection Properties.
For information on the projection of stream properties, see Working with Streams.
For information on the projection of object-valued properties, see Defining and Using Object-Valued Properties.
For information on the projection of relationships, see Defining and Using Relationships.

Identifiers for Saved Objects: ID and OID

Persistent Classes