Returns the highest value for a value expression for all records
specified by a record selection expression.
1 – Examples
The following programs demonstrate the use of the MAX function in
an assignment statement. These programs:
o Declare a host variable, latest_degree
o Use the MAX function to compute the highest number stored in
YEAR_GIVEN in the DEGREES relation
o Assign this computed value to the host variable
o Print an informational message and the value computed by the
MAX function
1.1 – C Example
#include <stdio.h>
DATABASE PERS = FILENAME "PERSONNEL";
main()
{
DECLARE_VARIABLE latest_degree SAME AS DEGREES.YEAR_GIVEN;
READY PERS;
START_TRANSACTION READ_ONLY;
GET
latest_degree = MAX D.YEAR_GIVEN OF D IN DEGREES;
END_GET;
printf ("Latest Degree was awarded in: %d\n", latest_degree);
COMMIT;
FINISH;
}
1.2 – Pascal Example
program assignmax (input,output);
DATABASE PERS = FILENAME 'PERSONNEL';
var
DECLARE_VARIABLE latest_degree SAME AS DEGREES.YEAR_GIVEN;
begin
READY PERS;
START_TRANSACTION READ_ONLY;
GET
latest_degree = MAX D.YEAR_GIVEN OF D IN DEGREES;
END_GET;
writeln ('Latest Degree was awarded in: ', latest_degree);
COMMIT;
FINISH;
end.
2 – Format
(B)0[m
q> [4mMAX[m qqqqqqqqqwq>qqqqqqqqqqqqqqqqqqwqqqqqqqqqqqqqqqqqqqqqqqqqk
mq> handle-options qqj x
x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
x
mqqqqqqqq> value-expr qqqq> [4mOF[m qqqq> rse qqqqqqqqqqqqq>
(B)0[mhandle-options =
q> ( qwqqqqqq> [4mREQUEST_HANDLE[m qqqqq> var qqqqqqqqwq> ) q>
tqqqqqq> [4mTRANSACTION_HANDLE[m qqq> var qqqqqqqqu
mqqqqqq> [4mREQUEST_HANDLE[m q> var q> , qqqqqqqk x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj x
mqqqq> [4mTRANSACTION_HANDLE[m q> var qqqqqqqqqqqj
2.1 – Format arguments
value-expr A value expression. A symbol or a string
of symbols used to calculate a value. When
you use a value expression in a statement,
Oracle Rdb calculates the value associated
with the expression and uses that value
when executing the statement.
rse A record selection expression. A phrase
that defines specific conditions that
individual records must meet before
Oracle Rdb includes them in a record stream.
handle-options A request handle, a transaction handle, or
both.
REQUEST_HANDLE var The REQUEST_HANDLE keyword followed by a
host language variable. A request handle
identifies a compiled Oracle Rdb request.
If you do not supply a request handle
explicitly, RDML associates a unique
request handle for the compiled request.
TRANSACTION_HANDLE The TRANSACTION_HANDLE keyword followed by
var a host language variable. A transaction
handle identifies a transaction. If
you do not supply a transaction handle
explicitly, RDML uses the default
transaction handle.