Conversion rules

The CODASYL definitions are converted to relational schema information according to the following rules.

No.	CODASYL subschema	Relational schema description
1	Record type	Base table identified with TABLE .... Name of the base table: record-type-name
2	Record type that is owner record type in at least one set	Primary key: record-type-name_ of data type INTEGER Additional information: PRIMARY KEY SYSTEMDEFINED Null-value condition: NOT NULL
3	Item of a record type	Field of the base table of the corresponding data type with null-value condition: NOT NULL Default value: 0 for numeric fields ''BLANK'' for alphanumeric fields
4	Group item, repeating group	Data type STRUCTURE
5	Repeating factor	(repeating factor)
6	Item of type DATABASE-KEY	Field of the base table with the same name Data type: INTEGER Default value: 0
7	Item of type DATABASE-KEY-LONG	Field of the base table with the same name Data type: CHARACTER ; length 8 Additional information: ATTRIBUTE item-name IS DEFINED AS DATABASE-KEY-LONG; default value: X'00..00'
8	One or more SYSTEM sets not defined MANDATORY AUTOMATIC	A base table with the name SYSTEM and primary key SYSTEM_ , of data type INTEGER
9	Set relationship	Foreign key in the base table that corresponds to the member record type Field name: set-name_ Data type: INTEGER Reference condition: REFERENCES owner-record-type-name
10	Set: MANDATORY AUTOMATIC	Foreign key with null-value condition: NOT NULL
11	Set: MANDATORY MANUAL	Foreign key with null-value condition: NOT NULL ON UPDATE Default value: NULL
12	Set: OPTIONAL AUTOMATIC	Foreign key with null-value condition: NOT NULL ON INSERT
13	Set: OPTIONAL MANUAL	Foreign key without null-value condition Default value: NULL
14	Key consisting of one or more items. e.g. for compound keys:	Additional information: left-hand column: INDEX ([set-name_,]group-name) right-hand column: INDEX ([set-name_,]field-1,...,field-n)
15	Unique key at record type level consisting of one item	Additional information UNIQUE for the key field
16	Unique key at set level consisting of one item for a SYSTEM set defined with MANDATORY AUTOMATIC	Additional information UNIQUE for the key field
17	Unique key at record type level consisting of multiple items	Additional information UNIQUE for the corresponding base table: UNIQUE (item-1,...,item-n)
18	Unique key at set level consisting of multiple items for a SYSTEM set defined with MANDATORY AUTOMATIC	Additional information UNIQUE for the base table corresponding to the member record type: UNIQUE (item-1,...,item-n)
19	Unique key at set level consisting of one or more items for a set defined with MANDATORY AUTOMATIC, or for a SYSTEM set not defined with MANDATORY AUTOMATIC	Additional information UNIQUE for the base table corresponding to the member record type: UNIQUE (set-name_,item-1,...,item-n) where set-name_ is the associated foreign key attribute

Table 15: Conversion rules for BPSQLSIA                                                                                                                                


The name of the CODASYL subschema becomes the name of the relational schema.Hyphens in names in the CODASYL schema are replaced by underscores in the derived names in the relational schema information.
Condition names (level number 88) are not output in the relational schema information.

Examples of the individual rules can be found on "Example".

The meanings of the relational terms and concepts are explained with examples in the “SQL for UDS/SQL“ manual.