Deletes one or more field definitions.  When the DELETE FIELD
 statement executes, Rdb/VMS deletes the field definition from the
 physical database.  If you invoke the database using the PATHNAME
 argument, Rdb/VMS also deletes the field definition from the
 CDD$DATABASE definition of the database in the data dictionary.  You
 can delete any named field, whether it was defined with a DEFINE
 FIELD statement or with a DEFINE RELATION statement.  However, you
 cannot delete a field that is referred to in the definition of a
 relation, index, or constraint:

 Example:

      DELETE FIELD POSTAL_CODE.

Additional information available:

MoreFormatExamples

  o  You must have the Rdb/VMS DELETE privilege for a field to delete
     the field with the DELETE FIELD statement.

  o  If you want to delete a field that is part of a relation
     definition, you must use the CHANGE RELATION statement to delete
     the field from the relation definition, or you must delete the
     entire relation.

  o  If you want to delete a field that is referred to in a constraint
     or index definition, you must first delete the constraint or
     index.

  o  You cannot delete a field definition unless you have invoked the
     database that includes the field.

  o  You can delete a field definition even when there are active
     users.  Deleting a field definition will not affect active users
     until they exit their session and invoke the database the next
     time.  By default, a database can be opened automatically (that
     is, by any user who invokes the database and executes a data
     manipulation language statement).  If the database was modified
     so that it must be manually opened, the RMU/OPEN command must be
     used to open it.

  o  You must execute this statement in a read/write transaction.  If
     there is no active transaction and you issue this statement,
     Rdb/VMS starts a read/write transaction implicitly.

 DELETE FIELD ───┬───> field-name ────┬───> .
                 └────<──── , ────<───┘

 field-name  The name of the field whose definition you want to
             delete.

 Example 1

 Delete a single field definition:

 RDO> INVOKE DATABASE PATHNAME 'PERSONNEL'
 RDO> START_TRANSACTION READ_WRITE
 RDO> DELETE FIELD TEMP_NUM.
 RDO> COMMIT

 This sequence deletes the field definition from the physical database
 and the data dictionary.


 Example 2

 Delete more than one field definition:

 RDO> INVOKE DATABASE PATHNAME 'PERSONNEL'
 RDO> START_TRANSACTION READ_WRITE
 RDO> DELETE FIELD TEMP_NUM, MONEY.
 RDO> COMMIT

 This sequence deletes the definitions for the TEMP_NUM and MONEY
 fields from the physical database and the data dictionary.


 Example 3

 Delete a field from a relation:

 RDO> INVOKE DATABASE PATHNAME 'PERSONNEL'
 RDO> START_TRANSACTION READ_WRITE
 RDO> DELETE FIELD STATUS_NAME.
 %RDO-W-NOCDDUPDAT, database invoked by filename, the CDD will not be
 updated
 %RDB-E-NO_META_UPDATE, metadata update failed
 %RDMS-F-RELEXI, field STATUS_NAME is used in relation, WORK_STATUS
 -RDMS-F-FLDNOTDEL, field STATUS_NAME has not been deleted
 RDO> CHANGE RELATION WORK_STATUS.
 cont>  DELETE STATUS_NAME.
 cont>  END.
 RDO> DELETE FIELD STATUS_NAME.
 RDO> COMMIT

 If a field is used in a relation, you need to perform two operations
 to delete it:

  o  Change the relation by deleting the field.

  o  Delete the global field definition.

 Example 4

 The following example shows that when a database is invoked by
 pathname and a database field based on a global field in the
 dictionary is deleted, the field is deleted from both the physical
 database and from the CDD$DATABASE definition of the database in the
 dictionary.  Note, however, that the global definition of the field
 in the dictionary is not deleted:

 $ DICTIONARY OPERATOR
 Welcome to CDO V1.3-2
 The CDD/Plus V4.3-2 User Interface
 Type HELP for help
 CDO> SET DEFAULT CDD$DEFAULT
 CDO> !
 CDO> ! Define the global field FIELD_1 in the dictionary:
 CDO> DEFINE FIELD FIELD_1
 cont> DATATYPE IS TEXT SIZE IS 7.
 CDO> DIRECTORY
  Directory RDO_USER:[RICH.DICT]
 CDD$PROTOCOLS                                    DIRECTORY
 CDD$RDB_SYSTEM_METADATA                          DIRECTORY
 FIELD_1;1                                        FIELD
 CDO> EXIT
 $ RDO
 RDO> ! Define the Rdb/VMS database MY_DATABASE.RDB, specifying the
 RDO> ! pathname where the CDD$DATABASE definition of MY_DATABASE.RDB
 RDO> ! will be stored:
 RDO> DEFINE DATABASE RDO_USER:[RICH]MY_DATABASE
 cont> IN RDO_USER:[RICH.DICT]MY_DATABASE.
 RDO> COMMIT
 %RDO-F-NO_TXNOUT, no transaction outstanding
 RDO> FINISH
 RDO> EXIT
 $ !
 $ ! Show that the CDD$DATABASE definition for the MY_DATABASE
 $ ! database now exists in the data dictionary:
 $ DICTIONARY OPERATOR
 Welcome to CDO V1.3-2
 The CDD/Plus V4.3-2 User Interface
 Type HELP for help
 CDO> SET DEFAULT CDD$DEFAULT
 CDO> DIRECTORY
  Directory RDO_USER:[RICH.DICT]
 CDD$PROTOCOLS                                    DIRECTORY
 CDD$RDB_SYSTEM_METADATA                          DIRECTORY
 FIELD_1;1                                        FIELD
 MY_DATABASE;1                                    CDD$DATABASE
 CDO> EXIT
 $
 $ ! Invoke the database by pathname and define FIELD_1 in the
 $ ! database, using the dictionary definition of FIELD_1:
 $ RDO
 RDO> INVOKE DATABASE PATHNAME RDO_USER:[RICH.DICT]MY_DATABASE
 RDO> !
 RDO> DEFINE FIELD FIELD_1
 cont> FROM PATHNAME RDO_USER:[RICH.DICT]FIELD_1.
 RDO> !
 RDO> SHOW FIELD FIELD_1
      FIELD_1                          text size is  7
    CDD pathname:        RDO_USER:[RICH.DICT]FIELD_1;1
 RDO> !
 RDO> ! Commit the definition of FIELD_1:
 RDO> COMMIT
 RDO> FINISH
 RDO> EXIT
 $ !
 $ DICTIONARY OPERATOR
 Welcome to CDO V1.3-2
 The CDD/Plus V4.3-2 User Interface
 Type HELP for help
 CDO> ! Show that the FIELD_1 definition is part of the
 CDO> ! CDD$DATABASE definition for MY_DATABASE.RDB in
 CDO> ! the dictionary:
 CDO> SHOW GENERIC CDD$DATABASE/FULL MY_DATABASE
 Definition of MY_DATABASE   (Type : CDD$DATABASE)
 |   Contains CDD$DATABASE_FILE
 |   |   RDO_USER:[RICH]MY_DATABASE      (Type : CDD$FILE)
 |   |   |   CDD$QUALIFIED_NAME              RDO_USER:[RICH]MY_DATABASE.RDB;
 |   Contains CDD$DATABASE_SCHEMA
 |   |   MY_DATABASE                     (Type : CDD$RDB_DATABASE)
            .
            .
            .
 |   |   |   Contains CDD$RDB_DATA_ELEMENT
 |   |   |   |   FIELD_1                         (Type : CDD$DATA_ELEMENT)
 |   |   |   |   |   CDD$DATA_ELEMENT_DATATYPE       14
 |   |   |   |   |   CDD$DATA_ELEMENT_LENGTH         7
            .
            .
            .
 CDO> EXIT
 $ !
 $ ! Invoke MY_DATABASE.RDB by pathname and delete the FIELD_1
 $ ! definition from the database (this also deletes the
 $ ! FIELD_1 definition from the CDD$DATABASE definition
 $ ! of MY_DATABASE.RDB in the dictionary):
 RDO> INVOKE DATABASE PATHNAME RDO_USER:[RICH.DICT]MY_DATABASE
 RDO> !
 RDO> DELETE FIELD FIELD_1.
 RDO> !
 RDO> ! The definition of FIELD_1 no longer exists in the physical
 RDO> ! database MY_DATABASE.RDB:
 RDO> SHOW FIELD FIELD_1
  No Fields Found
 RDO> COMMIT
 RDO> FINISH
 RDO> EXIT
 $ !
 $ DICTIONARY OPERATOR
 Welcome to CDO V1.3-2
 The CDD/Plus V4.3-2 User Interface
 Type HELP for help
 CDO> ! The global definition of FIELD_1 still exists in
 CDO> ! in the dictionary:
 CDO> SET DEFAULT CDD$DEFAULT
 CDO> DIRECTORY
  Directory RDO_USER:[RICH.DICT]
 CDD$PROTOCOLS                                    DIRECTORY
 CDD$RDB_SYSTEM_METADATA                          DIRECTORY
 FIELD_1;1                                        FIELD
 MY_DATABASE;1                                    CDD$DATABASE
 CDO> !
 CDO> ! Although the global definition of FIELD_1 still exists in the
 CDO> ! dictionary, the definition of FIELD_1 no longer exists in the
 CDO> ! the CDD$DATABASE definition of MY_DATABASE.RDB in the dictionary:
 CDO> SHOW GENERIC CDD$DATABASE /FULL MY_DATABASE
 Definition of MY_DATABASE   (Type : CDD$DATABASE)
 |   Contains CDD$DATABASE_FILE
 |   |   RDO_USER:[RICH]MY_DATABASE      (Type : CDD$FILE)
 |   |   |   CDD$QUALIFIED_NAME              RDO_USER:[RICH]MY_DATABASE.RDB;
 |   Contains CDD$DATABASE_SCHEMA
 |   |   MY_DATABASE                     (Type : CDD$RDB_DATABASE)
            .
            .
            .
 CDO> EXIT