Occurrences in MU and PE

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1

Is there an explanation on this ? I don’t understand the questions.

Given the following count and occurrences of a multiple value field whose elements are 4 byte numeric values:
x(5) x(2345) x(4567) x(5678) x(1256) x(5902)
what is the count field after this statement is executed?
MOVE 0 TO MU-FIELD(4)

Given the following count and occurrences of a multiple value field whose elements are 10 byte alphanumeric values:
x(3) x(SCHOOL) x(UNIVERSITY) x(COLLEGE)
what is the count field after this statement is executed?
MOVE ‘ACADEMY’ TO MU-FIELD(8)

2

There are a variety of factors involved:

  1. within the Natural program, the MU count does not change. That is, doing the MOVE does not update the MU count. The MU count (C*MU) is set by the database.
  2. if you UPDATE the record after modifying it as shown, the database record MAY change its MU count, depending on the suppression options of the field. For a NULL-SUPPRESSED (NU) field, setting an occurrence of the MU to a nullable value (0 for numeric, blank for alpha, binary 0 for binary) will cause the occurrence to be removed and the MU count decremented accordingly. If the field is not null suppressed, then the occurrence remains where it was and the MU counter is unchanged.

Changing the length of an element does not change the occurrence count (unless the element is set to a zero length value, of course).

If the MU count is 4 and you


   MOVE 'ACADEMY' TO MU-FIELD(08) 
   UPDATE (find-line.)

then if the field is not null suppressed (FI, normal compression), then the MU count will become 8. If the field is null suppressed (NU), then the MU count will become 5 - the “8th” occurrence will be moved down to the 5th.