Subschema Statements › RECORD Statement › Usage

Usage

Effect of ADD on Records

ADD copies the record description from the schema description into the subschema. The record can be copied into the subschema with its primary name or with any of its synonyms.

Note: A record description can be copied only once into a subschema, regardless of the number of record synonyms that exist for that record.

The following illustrates the use of the ADD RECORD statement. The left-hand side illustrates the original schema record description. The right-hand side illustrates a subschema record description, a subset of the schema.

SCHEMA                                       SUBSCHEMA

ADD RECORD NAME IS EMPOSITION             ADD RECORD NAME IS EMPOSITION
   LOCATION MODE IS VIA EMP-POSITION SET       STORE IS NOT ALLOWED
   WITHIN EMP-DEMO-REGION AREA.                ERASE IS NOT ALLOWED
   02 POS-START-DATE.                          ELEMENTS ARE
      03 POS-START-YEAR   PIC 99.                  POS-FINISH-DATE
      03 POS-START-MONTH  PIC 99.                  POS-START-DATE.
      03 POS-START-DAY    PIC 99.            ┌───────────────┬────────────────┐
   02 POS-FINISH-DATE.                       │POS-FINISH-DATE│ POS-START-DATE │
      03 POS-FINISH-YEAR  PIC 99.            └───────────────┴────────────────┘
      03 POS-FINISH-MONTH PIC 99.
      03 POS-FINISH-DAY   PIC 99.
   02 POS-SALARY-GRADE    PIC 99.
   02 POS-SALARY-AMOUNT   PIC S9(7)V99 COMP-3.
   02 POS-BONUS-PERCENT   PIC S999 COMP-3.
   02 POS-COMM-PERCENT    PIC S999 COMP-3.
   02 POS-OVERTIME-RATE   PIC S999 COMP-3.
   ┌──────────────┬───────────────┬──┬─────────────┐
   │POS-START-DATE│POS-FINISH-DATE│  │             │
   ├─────┬─────┬──┴─┬─────────────┴──┴─────────────┘
   │     │     │    │               ▲       ▲
   └─────┴─────┴────┘   POS-SALARY-GRADE    │
      ▲     ▲     ▲     POS-SALARY-AMOUNT -─┘
      │     │     └──── POS-OVERTIME-RATE
      │     └────────── POS-COMM-PERCENT
      └──────────────── POS-BONUS-PERCENT

Effect of DELETE on Records

DELETE removes the record from the current subschema description in the dictionary; the record remains associated with the schema.

How DELETE RECORD Affects Set Definitions

If the record owns a subschema set, DELETE RECORD deletes the set. If the record is a member of a subschema set, DELETE RECORD has no effect on the set.

The subschema DELETE RECORD statement does not affect the schema description of sets.

How ELEMENTS and VIEW ID Clauses Determine the Record Description

The combination of the ELEMENTS clause specification and the VIEW ID clause specification determines which fields are copied into the subschema description of database-record-name. The following table lists the possible combinations of the ELEMENTS clause and VIEW ID clause specifications and the resulting subschema view of the record.

Note: When the ELEMENTS clause is used for a view ID associated with other subschemas, the subschema compiler ignores the VIEW ID clause, creating a new subschema view with a null ID.

Considerations Specifying Fields in the ELEMENTS Clause

The following considerations apply to copying schema-defined fields into the subschema description of the record:

• Schema-defined fields can be named in any order in the ELEMENTS clause; the order in which they are named is the order in which they will participate in the subschema view of the record.
• If a group field is included in the subschema record description, all of its subordinate fields will be included and will retain their schema-defined order.
• FILLER fields cannot be included in the subschema record description, except as automatically included under groups.
• Redefining fields (or their subordinate fields) cannot be included in the subschema record description. Note, however, that if a redefined field is included, all redefining fields (and their subordinate fields) for that field will be included in the record description.
• Individual fields subordinate to an OCCURS field cannot be included in the record description. The OCCURS field itself must be included, in which case all fields subordinate to it will automatically be included as well.
• If an OCCURS DEPENDING ON field is included, the field on which that field depends must also be included in the record description.
• If an OCCURS DEPENDING ON field is included, it must be named last in the ELEMENTS clause.
• All fields named in the ELEMENTS clause must have the same level number.
• Bit fields cannot be included in the ELEMENTS clause.

PRIORITY Clause Can Optimize Use of Subschema Tables at Runtime

The PRIORITY clause permits the DBA to optimize runtime use of the subschema tables when a frequently used subschema includes many record types, of which only a few are used heavily. Those records used most heavily should be assigned high priorities. The PRIORITY clause is useful primarily in subschemas in which only a few record types are accessed frequently.