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Oracle PL/SQL Programming: A Developer's Workbook
book

Oracle PL/SQL Programming: A Developer's Workbook

by Steven Feuerstein, Andrew Odewahn
May 2000
Intermediate to advanced content levelIntermediate to advanced
594 pages
11h 32m
English
O'Reilly Media, Inc.
Content preview from Oracle PL/SQL Programming: A Developer's Workbook

Expert

Q:

28-33.

The following function is a possible solution for this problem. Note the use of the SUBSTR function to perform ASCII-to-HEX conversion:


/* Filename on web page: cgi_encode.sf */
CREATE OR REPLACE FUNCTION cgi_encode
   (s in VARCHAR2)
RETURN VARCHAR2 is

   ret_val VARCHAR2(32762) DEFAULT NULL;
   c CHAR(1);
   ld NUMBER DEFAULT 0;
   td NUMBER DEFAULT 0;
   a2h VARCHAR2(20) := '0123456789ABCDEF';
BEGIN
   FOR i IN 1..LENGTH(s) LOOP
      c := SUBSTR(s,i,1);

      IF ((UPPER(c) >= 'A' ) and ( UPPER(c) <= 'Z')) OR
         ((c >= '0') AND (c <= '9')) OR
          (c = '_')
      THEN
         ret_val := ret_val || c;
      ELSEIF c = ' ' then
         ret_val := ret_val || '+';
      ELSE
         ld := FLOOR( ASCII ( c ) / 16 );
         td := ASCII( c ) - 16*ld;
         ret_val := ret_val || '%';
         ret_val := ret_val || SUBSTR(a2h,ld+1,1);
         ret_val := ret_val || SUBSTR(a2h,td+1,1);
     END IF;

   END LOOP;
   RETURN ret_val;
EXCEPTION
   WHEN OTHERS THEN
      RETURN 'CONVERSION+ERROR';
END;

Q:

28-34.

The most likely cause of this problem is a buffer overflow. At the beginning of the time period, when there were just a few records, everything seemed to work fine. As more records were added, however, the system became noticeably slower. Finally, it exceeded the size of the HTML output buffer. Unfortunately, there is no PL/SQL workaround to this problem. A reasonable approach is to either break the file into sections or replace the PL/SQL procedure with a nonbuffered language such as Perl.

Q:

28-35.

The original ...

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Publisher Resources

ISBN: 9781449324070Supplemental ContentErrata Page