This document describes those Natural system functions which can be used in a program loop context.
It covers the following topics:
The following topics are covered:
Natural system functions may be specified in
assignment and arithmetic statements:
input/output statements:
that are used within any of the following statement blocks:
that is, for all FIND,
READ,
HISTOGRAM,
SORT or
READ WORK FILE
processing loops.
If a system function is used within an
AT END OF PAGE
statement, the corresponding DISPLAY statement must include the
GIVE SYSTEM
FUNCTIONS clause.
Records rejected by a WHERE clause are not
evaluated by a system function.
If system functions are evaluated from database fields which
originated from different levels of processing loops initiated with a
FIND, READ, HISTOGRAM or
SORT statement, the values are always processed according to their
position in the loop hierarchy. For example, values for an outer loop will only
be processed when new data values have been obtained for that loop.
If system functions are evaluated from user-defined variables,
the processing is dependent on the position in the loop hierarchy where the
user-defined variable was introduced in reporting mode. If the user-defined
variable is defined before any processing loop is initiated, it will be
evaluated for system functions in the loop where the AT BREAK,
AT END OF DATA or AT END OF PAGE statement is
defined. If a user-defined variable is introduced within a processing loop it
will be processed the same as a database field from that processing.
For selective referencing of system function evaluation for user-defined variables it is recommended to specify a loop reference with the user-defined variable to indicate in which loop the value is to be processed. The loop reference may be specified as a statement label or source code line number.
In general, the format and length of the system functions
AVER,
NAVER,
SUM and
TOTAL are the same as the
field to which they are applied. The output length of the field must be long
enough (either by default or user-specified) to hold any overflow digits. If
any arithmetic overflow occurs, an error message will be issued.
The following applies:
If the field is not long enough, use the
NL option of the
SORT GIVE
statement to increase the output length as follows:
SUM(field)(NL=nn)
This will not only increase the output length but also causes the field to be made longer internally.
For a field of format N, the format of the system function will be of format P (with the same length as the field).
When the system function is written to a work file
(WRITE WORK
FILE statement), the internal length of the field is
increased by one digit for numeric fields (format N or P), for example,
SUM of a field of format P3 is increased to P4. This has to be
taken into consideration when reading the work file.
System functions may also be referenced when they have been
evaluated in a GIVE clause of a
SORT statement.
For a reference to a system function evaluated with a SORT
GIVE statement, the name of the system function must be prefixed with an
asterisk (*).
Statement referencing is also available for system functions (see also Referencing of Database Fields Using (r) Notation in the section User-Defined Variables of the Programming Guide).
By using a statement label or the source-code line number (r) you can determine in which processing loop the system function is to be evaluated for the specified field.
| Format/length: | Same as field.
Exception: See Format/Length Requirements for AVER, NAVER, SUM and TOTAL. |
This system function contains the average of all values
encountered for the field specified with AVER. AVER
is updated when the condition under which AVER was requested is
true.
| Format/length: | P7 |
COUNT is incremented by 1 on each pass through the
processing loop in which it is located. COUNT is incremented
regardless of the value of the field specified with COUNT.
| Format/length: | Same as field. |
This system function contains the maximum value encountered for
the field specified with MAX. MAX is updated (if
appropriate) each time the processing loop in which it is contained is
executed.
| Format/length: | Same as field. |
This system function contains the minimum value encountered for
the field specified with MIN. MIN is updated (if
appropriate) each time the processing loop in which it is located is
executed.
| Format/length: | Same as field.
Exception: See Format/Length Requirements for AVER, NAVER, SUM and TOTAL. |
This system function contains the average of all values -
excluding null values - encountered for the field specified with
NAVER. NAVER is updated when the condition under
which NAVER was requested is true.
| Format/length: | P7 |
NCOUNT is incremented by 1 on each pass through the
processing loop in which it is located unless the value of the field specified
with NCOUNT is a null value.
Whether the result of NCOUNT is an array or a scalar
value depends on its argument (field). The number of the resulting occurrences
is the same as of field.
| Format/length: | Same as field. |
This system function contains the minimum value encountered -
excluding null values - for the field specified with NMIN.
NMIN is updated (if appropriate) each time the processing loop in
which it is located is executed.
| Format/length: | Same as field. |
This system function contains the value which the field specified
with OLD contained prior to a control break as specified in an
AT BREAK condition, or prior to the end-of-page or end-of-data
condition.
| Format/length: | Same as field.
Exception: See Format/Length Requirements for AVER, NAVER, SUM and TOTAL. |
This system function contains the sum of all values encountered
for the field specified with SUM. SUM is updated each
time the loop in which it is located is executed. When SUM is used
following an AT BREAK condition, it is reset after each value
break. Only values that occur between breaks are added.
| Format/length: | Same as field.
Exception: See Format/Length Requirements for AVER, NAVER, SUM and TOTAL. |
This system function contains the sum of all values encountered
for the field specified with TOTAL in all open processing loops in
which TOTAL is located.
The following examples are provided below:
Example 1 - AT BREAK Statement with Natural System Functions OLD, MIN, AVER, MAX, SUM, COUNT
Example 2 - AT BREAK Statement with Natural System Function AVER
Example 3 - AT END OF DATA Statement with System Functions MAX, MIN, AVER
Example 4 - AT END OF PAGE Statement with System Function AVER
** Example 'ATBEX3': AT BREAK (with Natural system functions)
************************************************************************
DEFINE DATA LOCAL
1 EMPLOY-VIEW VIEW OF EMPLOYEES
2 NAME
2 CITY
2 SALARY (1)
2 CURR-CODE (1)
END-DEFINE
*
LIMIT 3
READ EMPLOY-VIEW LOGICAL BY CITY = 'SALT LAKE CITY'
DISPLAY NOTITLE CITY NAME 'SALARY' SALARY(1) 'CURRENCY' CURR-CODE(1)
/*
AT BREAK OF CITY
WRITE / OLD(CITY) (EM=X^X^X^X^X^X^X^X^X^X^X^X^X^X^X)
31T ' MINIMUM:' MIN(SALARY(1)) CURR-CODE(1) /
31T ' AVERAGE:' AVER(SALARY(1)) CURR-CODE(1) /
31T ' MAXIMUM:' MAX(SALARY(1)) CURR-CODE(1) /
31T ' SUM:' SUM(SALARY(1)) CURR-CODE(1) /
35T COUNT(SALARY(1)) 'RECORDS FOUND' /
END-BREAK
/*
AT END OF DATA
WRITE 22T 'TOTAL (ALL RECORDS):'
T*SALARY TOTAL(SALARY(1)) CURR-CODE(1)
END-ENDDATA
END-READ
*
END
Output of program ATBEX3:
CITY NAME SALARY CURRENCY
-------------------- -------------------- ---------- --------
SALT LAKE CITY ANDERSON 50000 USD
SALT LAKE CITY SAMUELSON 24000 USD
S A L T L A K E C I T Y MINIMUM: 24000 USD
AVERAGE: 37000 USD
MAXIMUM: 50000 USD
SUM: 74000 USD
2 RECORDS FOUND
SAN DIEGO GEE 60000 USD
S A N D I E G O MINIMUM: 60000 USD
AVERAGE: 60000 USD
MAXIMUM: 60000 USD
SUM: 60000 USD
1 RECORDS FOUND
TOTAL (ALL RECORDS): 134000 USD
** Example 'ATBEX4': AT BREAK (with Natural system functions)
************************************************************************
DEFINE DATA LOCAL
1 EMPLOY-VIEW VIEW OF EMPLOYEES
2 NAME
2 CITY
2 SALARY (2)
*
1 #INC-SALARY (P11)
END-DEFINE
*
LIMIT 4
EMPL. READ EMPLOY-VIEW BY CITY STARTING FROM 'ALBU'
COMPUTE #INC-SALARY = SALARY (1) + SALARY (2)
DISPLAY NAME CITY SALARY (1:2) 'CUMULATIVE' #INC-SALARY
SKIP 1
/*
AT BREAK CITY
WRITE NOTITLE
'AVERAGE:' T*SALARY (1) AVER(SALARY(1)) /
'AVERAGE CUMULATIVE:' T*#INC-SALARY AVER(EMPL.) (#INC-SALARY)
END-BREAK
END-READ
*
END
Output of program ATBEX4:
NAME CITY ANNUAL CUMULATIVE
SALARY
-------------------- -------------------- ---------- ------------
HAMMOND ALBUQUERQUE 22000 42200
20200
ROLLING ALBUQUERQUE 34000 65200
31200
FREEMAN ALBUQUERQUE 34000 65200
31200
LINCOLN ALBUQUERQUE 41000 78700
37700
AVERAGE: 32750
AVERAGE CUMULATIVE: 62825
** Example 'AEDEX1S': AT END OF DATA
************************************************************************
DEFINE DATA LOCAL
1 EMPLOY-VIEW VIEW OF EMPLOYEES
2 PERSONNEL-ID
2 NAME
2 FIRST-NAME
2 SALARY (1)
2 CURR-CODE (1)
END-DEFINE
*
LIMIT 5
EMP. FIND EMPLOY-VIEW WITH CITY = 'STUTTGART'
IF NO RECORDS FOUND
ENTER
END-NOREC
DISPLAY PERSONNEL-ID NAME FIRST-NAME
SALARY (1) CURR-CODE (1)
/*
AT END OF DATA
IF *COUNTER (EMP.) = 0
WRITE 'NO RECORDS FOUND'
ESCAPE BOTTOM
END-IF
WRITE NOTITLE / 'SALARY STATISTICS:'
/ 7X 'MAXIMUM:' MAX(SALARY(1)) CURR-CODE (1)
/ 7X 'MINIMUM:' MIN(SALARY(1)) CURR-CODE (1)
/ 7X 'AVERAGE:' AVER(SALARY(1)) CURR-CODE (1)
END-ENDDATA
/*
END-FIND
*
END
Output of program AEDEX1S:
PERSONNEL NAME FIRST-NAME ANNUAL CURRENCY
ID SALARY CODE
--------- -------------------- -------------------- ---------- --------
11100328 BERGHAUS ROSE 70800 DM
11100329 BARTHEL PETER 42000 DM
11300313 AECKERLE SUSANNE 55200 DM
11300316 KANTE GABRIELE 61200 DM
11500304 KLUGE ELKE 49200 DM
SALARY STATISTICS:
MAXIMUM: 70800 DM
MINIMUM: 42000 DM
AVERAGE: 55680 DM
** Example 'AEPEX1S': AT END OF PAGE (structured mode)
************************************************************************
DEFINE DATA LOCAL
1 EMPLOY-VIEW VIEW OF EMPLOYEES
2 PERSONNEL-ID
2 NAME
2 JOB-TITLE
2 SALARY (1)
2 CURR-CODE (1)
END-DEFINE
*
FORMAT PS=10
LIMIT 10
READ EMPLOY-VIEW BY PERSONNEL-ID FROM '20017000'
DISPLAY NOTITLE GIVE SYSTEM FUNCTIONS
NAME JOB-TITLE 'SALARY' SALARY(1) CURR-CODE (1)
/*
AT END OF PAGE
WRITE / 28T 'AVERAGE SALARY: ...' AVER(SALARY(1)) CURR-CODE (1)
END-ENDPAGE
END-READ
*
END
Output of program AEPEX1S:
NAME CURRENT SALARY CURRENCY
POSITION CODE
-------------------- ------------------------- ---------- --------
CREMER ANALYST 34000 USD
MARKUSH TRAINEE 22000 USD
GEE MANAGER 39500 USD
KUNEY DBA 40200 USD
NEEDHAM PROGRAMMER 32500 USD
JACKSON PROGRAMMER 33000 USD
AVERAGE SALARY: ... 33533 USD