Redefinition is used to change the format of a field, or to divide a single field into segments.
This document covers the following topics:
The REDEFINE option of the
DEFINE DATA
statement can be used to redefine a single field - either a user-defined
variable or a database field - as one or more new fields. A group can also be
redefined.
Important:
Dynamic variables are not allowed in a redefinition.
The REDEFINE option redefines byte positions of a field
from left to right, regardless of the format. Byte positions must match between
original field and redefined field(s).
The redefinition must be specified immediately after the definition of the original field.
In the following example, the database field BIRTH is
redefined as three new user-defined variables:
DEFINE DATA LOCAL
01 EMPLOY-VIEW VIEW OF STAFFDDM
02 NAME
02 BIRTH
02 REDEFINE BIRTH
03 #BIRTH-YEAR (N4)
03 #BIRTH-MONTH (N2)
03 #BIRTH-DAY (N2)
END-DEFINE
...
In the following example, the group #VAR2, which consists
of two user-defined variables of format N and P respectively, is redefined as a
variable of format A:
DEFINE DATA LOCAL 01 #VAR1 (A15) 01 #VAR2 02 #VAR2A (N4.1) 02 #VAR2B (P6.2) 01 REDEFINE #VAR2 02 #VAR2RD (A10) END-DEFINE ...
With the notation FILLER
nX you can define
n filler bytes - that is, segments which are not to
be used - in the field that is being redefined. (The definition of trailing
filler bytes is optional.)
In the following example, the user-defined variable #FIELD
is redefined as three new user-defined variables, each of format/length A2. The
FILLER notations indicate that the 3rd and 4th and 7th to 10th
bytes of the original field are not be used.
DEFINE DATA LOCAL 1 #FIELD (A12) 1 REDEFINE #FIELD 2 #RFIELD1 (A2) 2 FILLER 2X 2 #RFIELD2 (A2) 2 FILLER 4X 2 #RFIELD3 (A2) END-DEFINE ...
The following program illustrates the use of a redefinition:
** Example 'DDATAX01': DEFINE DATA ************************************************************************ DEFINE DATA LOCAL 01 VIEWEMP VIEW OF EMPLOYEES 02 NAME 02 FIRST-NAME 02 SALARY (1:1) * 01 #PAY (N9) 01 REDEFINE #PAY 02 FILLER 3X 02 #USD (N3) 02 #OOO (N3) END-DEFINE * READ (3) VIEWEMP BY NAME STARTING FROM 'JONES' MOVE SALARY (1) TO #PAY DISPLAY NAME FIRST-NAME #PAY #USD #OOO END-READ END
Output of Program DDATAX01:
Note how #PAY and the fields resulting from its definition
are displayed:
Page 1 04-11-11 14:15:54
NAME FIRST-NAME #PAY #USD #OOO
-------------------- -------------------- ---------- ---- ----
JONES VIRGINIA 46000 46 0
JONES MARSHA 50000 50 0
JONES ROBERT 31000 31 0