35) What are properties of entity type and attribute in GEN ? CoolGen, CA GEN

35) What are properties of entity type and attribute in GEN ? CoolGen, CA GEN


Every entity type and attribute in the Data Model has a Data Structure Definition (DSD) name, which is used for record, table, field and column names in the database structure as defined by the Data Structure List and Data Store List.  If you do not specify DSD names for your entity types and attributes, the entity type and attribute names from the Data Model are used by GEN as DSD names.

· Entity type names, attribute names, and DSD names may each be up to 32 characters in length.  However, table names and column names for generated DDL are limited to 18 characters.During Transformation, a table name or attribute name is derived from the DSD name and is referenced for records and fields in the Data Structure List.  To create the derived name from a DSD name, GEN will:

-Truncate the DSD name, if it is too long

-Add numbers as necessary to ensure uniqueness if the truncated name is not unique

-Add numbers to the name if it is reserved wordGEN does not allow special characters in entity names.  National language characters are supported in both entity names and DSD names.

· If no DSD name is specified for an entity type, the record and table are assigned the entity type's name.You can modify the record name, table name, or attribute name in the Data Structure List without affecting the DSD name in the Data Model.

· During database Transformation of an entity type, the record implementing the entity type is assigned the entity type's DSD name, if one exists, with length and reserved word checking.

· Avoid using Database Management System (DBMS) and target language reserved words for entity type or attribute names.  If you use a DBMS reserved word in the Data Model, GEN changes it during Transformation.  DBMS reserved words are checked again during Data Definition Language (DDL) generation and during code generation, since you may install on multiple platforms with the same database structure.  If the database structure is changed after Transformation, the change(s) are not used in Retransformation unless the Data Model is also changed.

· Other entity type properties describe the estimated number of entities and the anticipated increase in that number (growth rate).  GEN uses the volume and activity measurements to calculate dataset sizes during database Transformation.  Use anticipated sizes for production during data analysis.  Generated DDL may be adjusted to reduce space for testing.For related information, refer to the section on Transformation Calculations in the chapter Database Design.