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HP COBOL
DBMS Database Programming Manual

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DISCONNECT

Function

The DISCONNECT statement logically removes the current record of the run unit from one or more sets.

record-name

names a subschema record type.

set-name

names a subschema set type.

stment

is an imperative statement executed for an on error condition.

stment2

is an imperative statement executed for a not on error condition.

Syntax Rules

  1. The record type of record-name must be a member record type of the set type for each set-name.
  2. The same set-name cannot be specified more than once in the same DISCONNECT statement.

General Rules

  1. The DISCONNECT statement references the current record of the run unit.
  2. The current record of the run unit must be in a realm in ready mode and all records required by the DBCS to execute the DISCONNECT statement must be in a realm in available mode.
  3. Use record-name to check that the current record of the run unit has the same record type as record-name.
  4. The current record of the run unit must be an OPTIONAL member of each set-name.
  5. The record type of the current record of the run unit must be a member record type of the set type for each set-name.
  6. The DBCS removes the current record of the run unit from each set-name.
  7. Use the ALL clause to remove the current record of the run unit from as many sets as possible. The DBCS considers only those set types defined in the subschema for which the record is an OPTIONAL member. Set types not included in your subschema and set types of which the record is not a member are ignored. The current record of the run unit is removed from each remaining set type.
  8. If the set type currency indicator for a disconnected set pointed to the current record, that currency indicator now points to the position in the set vacated by the record. All other currency indicators are not affected.
  9. If the execution of a DISCONNECT statement results in a database exception condition, no changes are made to the membership of the current record in the database.
  10. If a database exception condition occurs during the execution of a DISCONNECT statement, the DBCS places a database exception condition code in the special register DB-CONDITION (see Technical Notes). This code identifies the condition.

Technical Notes

DISCONNECT statement execution can result in these DB-CONDITION database exception condition codes:

DBM$_NOT_OPTNL The current record of the run unit is not an OPTIONAL member of set-name.
DBM$_CRUN_NULL The currency indicator for the current record of the run unit is null.
DBM$_CRUN_POS The currency indicator for the current record of the run unit specifies the position of a vacated record in a record collection.
DBM$_WRONGRTYP The record type of record-name is not the same as the current record's type.
DBM$_NOT_MTYP The current record is not a member record type of set-name.
DBM$_NOT_MBR The current record is not a member of set-name.
DBM$_NOT_UPDATE A realm is not in ready update usage mode.

Additional References

  • Section 2.2 on reserved words (database special registers)
  • HP COBOL Reference Manual, Chapter 6, section on scope of statements
  • Section 4.8.1, on database On Error condition
  • USE statement

Examples 


DISCONNECT EMPLOYEE FROM CONSISTS_OF.

DISCONNECT EMPLOYEE FROM ALL.

DISCONNECT FROM ALL.

DISCONNECT FROM CONSISTS_OF.

ERASE

Function

The ERASE statement deletes the current record of the run unit from the database. Additional records owned by the current record may also be deleted and/or disconnected.

record-name

names a subschema record type.

stment

is an imperative statement executed for an on error condition.

stment2

is an imperative statement executed for a not on error condition.

General Rules

  1. The ERASE statement references the current record of the run unit.
  2. Use record-name to check that the current record of the run unit has the same record type as record-name.
  3. The current record of the run unit must be in a realm in update ready mode, and all records required by the Database Control System (DBCS) to execute the ERASE statement must be in a realm in available mode.
  4. The current record of the run unit is called the object record for the remaining General Rules.
  5. The object record is erased from all sets in which it is a member and deleted from the database.
  6. If you use the ALL phrase, the object record and all sets owned by the object record are erased (independent of set membership retention class).
  7. If you do not use the ALL phrase, these rules apply to the members of the sets owned by the erased object record:
    • Each member with FIXED membership is erased.
    • Each member with OPTIONAL membership is disconnected from the set but not deleted from the database.
    • An exception occurs if any members have MANDATORY membership.
  8. The database key value corresponding to the erased object record is removed from all keeplists.
  9. General Rules 5 to 8 apply to each erased record as if it were the object record.
  10. The successful ERASE statement changes currency indicators as follows:
    • The currency indicator for the current record of the run unit points to the position in the database vacated by the current record of the run unit. However, you no longer have a current record.
    • If an erased record is the current record of a disconnected set type, that set type currency indicator now points to the position in the set vacated by that record.
    • If an erased record is the owner of the current set of any set type, that set type's currency indicator becomes null.
    • If an erased record is the current record of a record type, that record type currency indicator becomes null.
    • If the erased record is the current record of the realm, that realm currency indicator now points to the position in the realm vacated by that record.
  11. If the execution of an ERASE statement results in a database exception condition, no changes are made to the database.
  12. If a database exception condition occurs during the execution of an ERASE statement, the DBCS places a database exception condition code in the special register DB-CONDITION (see Technical Notes). This code identifies the condition.

Technical Notes

ERASE statement execution can result in these DB-CONDITION database exception condition codes:

DBM$_CRUN_NULL The currency indicator for the run unit is null.
DBM$_CRUN_POS The currency indicator for the run unit specifies the position of a vacated record in the record collection.
DBM$_WRONGRTYP The record type of record-name is not the same as the current record's type.
DBM$_ERASEMANDT You attempted to erase a record that is the owner of a set occurrence with a MANDATORY member record occurrence, but you did not use the ALL option.
DBM$_NOT_UPDATE A realm is not in update usage mode.

Additional References

  • Section 2.2, on reserved words (database special registers)
  • HP COBOL Reference Manual, Chapter 6, section on scope of statements
  • Section 4.8.1, on database On Error condition
  • USE statement

Examples

  1. This example erases PART record, all records owned by PART in the PART_USES, PART_INFO, and PART_USED_ON sets. It also erases all SUPPLY and PR_QUOTE records that it owns through the PART_INFO set. It disconnects PART from the RESPONSIBLE_FOR set. 


    ERASE PART.
  2. This example has the same effect as in example 1 for each PART record that the CLASS1 record owns; however, it also erases the CLASS1 record. 


    ERASE ALL CLASS1.

    Note
    Because CLASS1 has MANDATORY members, you cannot erase only CLASS1.

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