Expert

22-19.

Write a package that manages communication through a private pipe named “invasions”. Each message in the pipe contains the information as specified by the following query:

SELECT country, date_of_invasion, people_killed
  FROM invasions
 WHERE (invader IN ('USA', 'CHINA', 'GERMANY', 'SOVIET UNION')
   AND date_of_invasion > '01-JAN-1900';

Features of this package should include the following:

  • The user never specifies or knows the name of the pipe; it is hidden to avoid any spelling mistakes and to ensure consistency.

  • It create the pipe automatically when a session tries to use the pipe.

  • The list is a long one (including, for example, Grenada, Poland, Nicaragua, Vietnam, Chile, France, Tibet, Norway, El Salvador, and Iraq), so set the initial pipe size to at least 2 MB.

  • It waits up to 10 seconds to get or send the information.

Here is the package specification; you write the body:


/* Filename on web page: invasions.pkg */
CREATE OR REPLACE PACKAGE invasion
IS
   TYPE inv_rectype IS RECORD (
      country IN invasions.country%TYPE,
      date_of_invasion invasions.date_of_invasion%TYPE,
      people_killed invasions.people_killed%TYPE
      );

   PROCEDURE sendinfo (
      country IN VARCHAR2,
      date_of_invasion DATE,
      people_killed NUMBER
      );

   PROCEDURE sendinfo (rec IN inv_rectype);

   FUNCTION nextinfo RETURN inv_rectype;
END;
/

22-20.

How can you can obtain a list of all the currently defined database pipes to which you have ...

Get Oracle PL/SQL Programming: A Developer's Workbook now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial