Creates a global field definition.

 When the DEFINE FIELD statement executes, Rdb/VMS adds the field
 definition to the physical database.  A field definition is similar
 to a template for a field in a relation.  It includes a name, a data
 type, and a set of optional clauses.

 Example:

      DEFINE FIELD LABEL
         DATATYPE IS TEXT SIZE IS 8 CHARACTERS
         MISSING_VALUE IS "Not here"
         VALID IF LABEL =  "Good"       OR
                  LABEL =  "Bad"        OR
                  LABEL =  "Mediocre"   OR
                  LABEL MISSING
         QUERY_HEADER FOR DATATRIEVE IS "Column"/"Label".

Additional information available:

MoreFormatExamples

 If you have invoked the database with the PATHNAME specification, the
 field definition is also added to the data dictionary.  Once you have
 defined a field globally, any relation can use the field definition
 by using the field name in the DEFINE or CHANGE RELATION statement.

 You can copy a shareable field definition from the data dictionary
 into the database.


 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.

 Other users are allowed to be attached to the database when you issue
 the DEFINE FIELD statement.

 DEFINE FIELD ─────────> name ────────────────────>────────────────────┐
                                                                       │
 ┌───────────────────────────────<─────────────────────────────────────┘
 │
 └─┬────> 
F
R
O
M 
P
A
T
H
N
A
M
E ───────────────> path-name ──────>───────┬────> .
   │                                                             │
   └─┬───────────────>───────────────┬───> field-attributes ─────┘
     └─> 
D
E
S
C
R
I
P
T
I
O
N typebox (I)typebox (S) typebox (/)typebox (*) text */ ──┘

Additional information available:

namepath-nametextfield-attributes

 Name of the field you want to create.  You must use a field name that
 conforms to VMS naming conventions.

 A full or relative data dictionary path name, enclosed in quotation
 marks, specifying the source of the field definition.  You must
 invoke the database by path name if you plan to copy a shareable
 field definition from the data dictionary.

 The name you give to the field must match the name of the field in
 the data dictionary.  You cannot rename a shareable field.

 A text string that adds a comment to the field definition.

 A list of definitions that indicate what type of data you can store
 in the field and how Rdb/VMS uses that data.  The field attributes
 include the data type and the following optional clauses:

  o  VALID IF
  o  MISSING_VALUE
  o  DATATRIEVE support clauses

 Do not use multiple, conflicting clauses in a field definition.

 For a complete description of field attributes, ask for HELP on
 Field_attr.

 Example 1:  Using DEFINE FIELD

 DEFINE FIELD STANDARD_ID_NUMBER
     DATATYPE IS SIGNED LONGWORD.

 This statement gives a name to the field and specifies its data type.


 Example 2:  Using DEFINE FIELD with VALID IF

 DEFINE FIELD SEX
    DATATYPE IS TEXT SIZE IS 1
    VALID IF SEX = "M" OR SEX = "F".

 This definition provides validation criteria.  When a user tries to
 enter a value other than "M" or "F" in a field that refers to this
 definition, Rdb/VMS returns an error message.


 Example 3:  Using DEFINE FIELD with DATATRIEVE Support

 DEFINE FIELD SALARY_AMOUNT
     DATATYPE IS SIGNED LONGWORD
     DEFAULT_VALUE FOR DATATRIEVE IS 0
     EDIT_STRING FOR DATATRIEVE IS "$$$$,$$9.99".

 This example adds a DATATRIEVE edit string and default value to the
 name and data type.

 Example 4:  Copying a Field from the data dictionary

 DEFINE FIELD SALARY_AMOUNT
   FROM PATHNAME 'DISK1:[CDDPLUS.DEFS]PERS.SALARY_AMOUNT'.

 This example copies the shareable field, SALARY_AMOUNT, from the
 dictionary.