Using Dynamic SQL With Objects

3.4 Using Dynamic SQL With Objects

Dynamic SQL is a feature of PL/SQL that enables you to enter SQL information, such as a table name, the full text of a SQL statement, or variable information at run-time.

Topics:

3.4.1 Using Dynamic SQL with Object Types and Collections

You can use dynamic SQL with object types and collections.

Example 3-11 illustrates the use of objects and collections with dynamic SQL. First, the example defines the object type person_typ and the VARRAY type hobbies_var, then it defines the package, teams, that uses these types.

You need AUTHID CURRENT_USER to execute dynamic package methods; otherwise, these methods raise an insufficient privileges error when you run Example 3-12, which is an anonymous block that calls the procedures in package TEAMS.

Example 3-11 A Package that Uses Dynamic SQL for Object Types and Collections

CREATE OR REPLACE TYPE person_typ AS OBJECT (name VARCHAR2(25), age NUMBER);
/
CREATE TYPE hobbies_var AS VARRAY(10) OF VARCHAR2(25);
/
CREATE OR REPLACE PACKAGE teams

   AUTHID CURRENT_USER AS
   PROCEDURE create_table (tab_name VARCHAR2);
   PROCEDURE insert_row (tab_name VARCHAR2, p person_typ, h hobbies_var);
   PROCEDURE print_table (tab_name VARCHAR2);
END;
/
CREATE OR REPLACE PACKAGE BODY teams AS
   PROCEDURE create_table (tab_name VARCHAR2) IS
   BEGIN
      EXECUTE IMMEDIATE 'CREATE TABLE ' || tab_name ||
                        ' (pers person_typ, hobbs hobbies_var)';
   END;
   PROCEDURE insert_row (
      tab_name VARCHAR2,
      p person_typ,
      h hobbies_var) IS
   BEGIN
      EXECUTE IMMEDIATE 'INSERT INTO ' || tab_name ||
         ' VALUES (:1, :2)' USING p, h;
   END;
   PROCEDURE print_table (tab_name VARCHAR2) IS
      TYPE  refcurtyp IS REF CURSOR;
      v_cur refcurtyp;
      p     person_typ;
      h     hobbies_var;
   BEGIN
      OPEN v_cur FOR 'SELECT pers, hobbs FROM ' || tab_name;
      LOOP
         FETCH v_cur INTO p, h;
         EXIT WHEN v_cur%NOTFOUND;
         -- print attributes of 'p' and elements of 'h'
         DBMS_OUTPUT.PUT_LINE('Name: ' || p.name || ' - Age: ' || p.age);
         FOR i IN h.FIRST..h.LAST 
         LOOP
           DBMS_OUTPUT.PUT_LINE('Hobby(' || i || '): ' || h(i));
         END LOOP;
      END LOOP;
      CLOSE v_cur;
   END;
END;
/

3.4.2 Calling Package Procedures with Object Types and Collections

You can call package procedures with object types and collections.

From an anonymous block,Example 3-12, you might call the procedures in package TEAMS as shown in Example 3-11

Example 3-12 Calling Procedures from the TEAMS Package

DECLARE
   team_name VARCHAR2(15);
BEGIN
   team_name := 'Notables';
   TEAMS.create_table(team_name);
   TEAMS.insert_row(team_name, person_typ('John', 31),
      hobbies_var('skiing', 'coin collecting', 'tennis'));
   TEAMS.insert_row(team_name, person_typ('Mary', 28),
      hobbies_var('golf', 'quilting', 'rock climbing', 'fencing'));
   TEAMS.print_table(team_name);
END;
/