User's Manual

194 Appendix D. PDL Syntax
• retrieve — used to signify the beginning of the block of code defining the retrieve event. One
example of this would be a code block specifying how to retrieve an object of the defined type. It
can also be used with the keyword all to retrieve all objects of the defined type.
• returns — used to signify that a definition returns something. One example is returns within a
Data Query definition. In that case, it is used as an optional parameter in conjunction with two
values to indicate the number of rows that may be returned by the given query.
• super — used to designate calling the same named method within the parent category. This can
only be used when the object type extends another object type and is typically used within SQL
event declarations.
• to — a keyword, used in association with join, to define the way to join two database tables
together. In object types, sequences of join-to statements are defined to assist the metadata-driven
SQL system in generating the standard queries.
• true — the boolean value true.
• unique — signifies that only one object type may have a given value for the attribute or combina-
tion of attributes. It also tells the DDL Generator to create a unique constraint.
• unversioned — means that the versioning service should not version this attribute.
• update — the keyword used to signify the beginning of the block of code defining the update
event (for example, how to update an object of the defined type).
• versioned — when used in front of an object type, this keyword tells the versioning service to
version all instances of this type; when used in front of a compound attribute, this keyword tells
the versioning service to version this attribute, even though it would not normally be versioned
otherwise.
• White Space — the token used to signify spaces. That is, " ", "\t", "\n", "\r", or "\f".
D.2.2. PDL Attribute Types
The PDL Attribute Types are the allowed Java types for attributes defined in PDL. Therefore, every
type seen here is the Java type returned by the persistence system.
BigInteger
BigDecimal
Boolean
Byte
Character
Date
Double
Float
Integer
Long
Short
String // This should be used for both Strings and Clobs.
Blob // This actually returns a Byte[] and will be deprecated once
// the PDL compiler supports arrays.
D.3. PDL and SQL Used in the Tutorial
This section provides two examples, one each of SQL and PDL usage. These can be used as quick
references to the context of every SQL and PDL example throughout the WAF Developer Guide. The
PDL usage is first in Example D-1, with the SQL usage second in the Example D-2.