DEFINE FIELD command

Summary

Privileges

Any user

Function

Defines the names and attributes of the fields in a Model 204 file

Syntax

DEFINE [FIELD] name [(attribute [attribute]...)]

or

DEFINE [FIELD] name WITH [attribute [attribute]...]

Where:

name

(1 to 255 characters) must begin with a letter and can contain any alphanumeric characters (including space) except: ?? ?$ ?& @ (or an alternative delete character) # (or an alternative flush character)  ; name must not start with a reserved word or character. An embedded reserved word or character must be part of a string preceded and followed by a single quotation mark.

attribute

is one of the field characteristics listed in the table below. Note that each attribute has a default. Therefore, when selected, the attribute need be specified only if it differs from the default. If no attributes are specified, the field is defined with all the defaults. All attributes are described in the Model 204 File Manager's Guide. Field attributes Attribute Abbreviation Default AT-MOST-ONE REPEATABLE ONE REPT REPT (except in 1NF files) BINARY BIN Not a binary field BINARY-LARGE-OBJECT BLOB Not binary large object CHARACTER-LARGE-OBJECT CLOB Not character large object CODED NON-CODED COD NCOD NON-CODED DATETIME DT Data format YYYYMMDDHHMMSSXXXXXX (the nearest millionth of a second) DEFERRABLE NON-DEFERRABLE DEF NDEF DEFERRABLE FEW-VALUED MANY-VALUED FV MV MANY-VALUED FLOAT FL Not a floating point field FRV (for-each-value) NON-FRV -- NFRV NON-FRV KEY NON-KEY -- NKEY NON-KEY LENGTH m LEN No preallocated length LEVEL k LVL No level LRESERVE LRES 15 NRESERVE NRES 15 NUMERIC RANGE NON-RANGE RANGE, NR NNR NON-RANGE OCCURS n OCC No preallocated occurrences ORDERED NON-ORDERED ORD NON-ORD Non-ordered field ORDERED CHARACTER ORD CHAR -- ORDERED NUMERIC ORD NUM -- SPLITPCT SPLT 50 IMMED IMM 1 PAD character -- PAD X'00' STRING BINARY STR BIN STRING UPDATE IN PLACE UPDATE AT END UP UE UPDATE IN PLACE VISIBLE INVISIBLE VIS INV VISIBLE UNIQUE NON-UNIQUE UNIQ NUNIQ NON-UNIQUE

Conflicting attributes, listed in the table below, cannot be specified together.

Conflicting field attributes

This attribute...	Cannot be specified with the attribute(s)...
INVISIBLE	NON-KEY, NON-RANGE, and NON-ORDERED
INVISIBLE	UPDATE IN PLACE or UPDATE AT END
FRV	NON-KEY
NON-CODED and NON-FRV	MANY-VALUED or FEW-VALUED
NON-ORDERED, NON-KEY, and NON-RANGE	DEFERRABLE or NON-DEFERRABLE
CODED, BINARY, CLOB, and BLOB	LENGTH
NUMERIC RANGE	OCCURS n (if n > 1)
FLOAT	STRING, BINARY, NUMERIC RANGE, and INVISIBLE
OCCURS	INVISIBLE
ORDERED	FRV
ORDERED NUMERIC	NUMERIC RANGE
LRESERVE	NON-ORDERED
NRESERVE	NON-ORDERED
SPLITPCT	NON-ORDERED
IMMED	NON-ORDERED
UNIQUE	DEFERRABLE

Paired attributes, listed in the table below, must be specified together.

Paired field attributes

This attribute...	Must be specified with the attribute(s)...
FLOAT	LENGTH
OCCURS	CODED, BINARY, or LENGTH
PAD	LENGTH
UNIQUE	ORDERED

Syntax notes

Attributes must be separated by commas or by one or more blanks.

You can specify DEFINE FIELD only in file context.

Example

DEFINE FIELD CUSTID WITH KEY FRV RANGE DEFINE FIELD AGE WITH KEY RANGE OCCURS 1 LENGTH 3 DEFINE FIELD EMPLOYEE

Usage notes

The DEFINE FIELD command describes the names and attributes of the fields in a Model 204 file. The file must be initialized, using the INITIALIZE command, before fields can be defined.

Note: Sort key fields for sorted files, hash key fields, and record security fields can be defined only with the INITIALIZE command, not with DEFINE.

Once fields have been defined, a user with the requisite privileges can perform the following functions on them:

• Delete (DELETE command)

• Display (DISPLAY command)

• Redefine (REDEFINE command)

• Rename (RENAME command)

You can define three types of floating point fields through the FLOAT and LENGTH attributes. The table below shows the characteristics of the three types.

Types of floating point fields

Type	Number of bytes	Maximum number of significant digits
Short precision	4	6
Long precision	8	15
Extended precision	16	31

You supply a LENGTH attribute of 4, 8, or 16. The following example defines a long-precision floating-point field:

DEFINE FIELD SALARY WITH FLOAT LEN 8

Consider making a field a floating-point field if its value is always or often numerical. Very large numbers or numbers with many significant digits use much less space in floating-point form than they do in character form. Floating-point fields are valid only for files with the format of Release 8.0 or later or that have been converted by the TRANSFORM FLOAT command. Floating-point numbers in ORDERED NUMERIC trees are discussed as follows.

The ORDERED attribute is used to define fields for the Ordered Index feature. The ORDERED attribute can be followed by a tree type to specify the kind of ordering for the index. The tree type can be either CHARACTER (CHAR) or NUMERIC (NUM). If a tree type is not provided, a default tree type is used.

The format for the DEFINE FIELD command with solely the ORDERED option and its related attributes is as follows:

Syntax

DEFINE [FIELD] name WITH [ORDERED [CHARACTER | NUMERIC] [LRESERVE n] [NRESERVE n] [SPLITPCT n] [IMMED n]]

Where:

LRESERVE	defines the percentage of space to leave free on the leaf page during deferred updates or a REORGANIZE command. The default is 15 percent. The value must be between 0 and 99.
NRESERVE	defines the percentage of space to leave free on the node page during deferred updates or a REORGANIZE command. The default is 15 percent. The value must be between 0 and 99.
SPLITPCT	defines the percentage of the node data to go to the left node when a split occurs during nondeferred User Language or IFAM requests. The default is 50 percent. The value must be between 1 and 100.
IMMED	defines the number of immediate pointers per segment in the Ordered Index. The default is 1. The value must be between 0 and 255.

Usage notes

The LRESERVE, NRESERVE, SPLITPCT, and IMMED parameters represent approximate values. The actual movement of data during an update might not conform exactly to the value of the attribute in question.

The default ordering for a field is NON-ORDERED. Ordered Index attributes do not apply for a NON-ORDERED field.

If a field is defined as ORDERED without specifying the type of tree to create, the default depends on whether the field is STRING, BINARY, or FLOAT. If STRING, an ORDERED CHARACTER tree is defined. If FLOAT or BINARY, an ORDERED NUMERIC tree is defined.

The UNIQUE attribute specifies that there can be only one occurrence of a unique field in the file. Multiple occurrences are not allowed.

For a detailed discussion of field attributes, refer to the Model 204 File Manager's Guide.

Specifying the date/time stamp field name

The new system parameter DTSFN specifies the date/time stamp field name. This field name is the same for all files participating in DTS processing in a run. Though this is a system-level parameter, the feature is a file-level feature.

The date/time stamp field name you specify is not edited for validity.

The DTSFN value may be specified in CUST source code, so you do not have to change all your jobs to specify the parameter. In the Rocket Model 204 Parameter and Command Reference see "DTSFN: Name of the date/time stamp field." As shipped, Model 204 does not provide a field name.

Specifying a date/time stamp field definition

A date/time stamp field is defined as is any other Model 204 field. The restrictions on permissible field attributes are:

• May not be INVISIBLE or UNIQUE.

• If preallocated, OCCURS may not be greater than 1.

Disregarding these restrictions causes the following error:

M204.2728: DATE TIME STAMP FIELD MAY NOT BE INVISIBLE, UNIQUE, NOR HAVE MULTIPLE OCCURRENCES

Rocket Software recommends using the ORDERED CHARACTER attribute. By default Model 204 generates a character string date/time stamp field value.

Defining the date/time stamp field value format

Your custom code formats the data entered into the field. The format for the default date/time stamp string is:

CCYYMMDDHHMMSSMMM

Note: The DTSFN field may have differing definitions in different Model 204 databases.