7 PL/SQL Dynamic SQL

Example 7-1 Invoking Subprogram from Dynamic PL/SQL Block

-- Subprogram that dynamic PL/SQL block invokes:
CREATE OR REPLACE PROCEDURE create_dept (
  deptid IN OUT NUMBER,
  dname  IN     VARCHAR2,
  mgrid  IN     NUMBER,
  locid  IN     NUMBER
) AUTHID DEFINER AS
BEGIN
  deptid := departments_seq.NEXTVAL;

  INSERT INTO departments (
    department_id,
    department_name,
    manager_id,
    location_id
  )
  VALUES (deptid, dname, mgrid, locid);
END;
/
DECLARE
  plsql_block VARCHAR2(500);
  new_deptid  NUMBER(4);
  new_dname   VARCHAR2(30) := 'Advertising';
  new_mgrid   NUMBER(6)    := 200;
  new_locid   NUMBER(4)    := 1700;
BEGIN
 -- Dynamic PL/SQL block invokes subprogram:
  plsql_block := 'BEGIN create_dept(:a, :b, :c, :d); END;';

 /* Specify bind variables in USING clause.
    Specify mode for first parameter.
    Modes of other parameters are correct by default. */

  EXECUTE IMMEDIATE plsql_block
    USING IN OUT new_deptid, new_dname, new_mgrid, new_locid;
END;
/

Example 7-2 Dynamically Invoking Subprogram with BOOLEAN Formal Parameter

CREATE OR REPLACE PROCEDURE p (x BOOLEAN) AUTHID DEFINER AS
BEGIN
  IF x THEN
    DBMS_OUTPUT.PUT_LINE('x is true');
  END IF;
END;
/

DECLARE
  dyn_stmt VARCHAR2(200);
  b        BOOLEAN := TRUE;
BEGIN
  dyn_stmt := 'BEGIN p(:x); END;';
  EXECUTE IMMEDIATE dyn_stmt USING b;
END;
/

Result:

x is true

Example 7-3 Dynamically Invoking Subprogram with RECORD Formal Parameter

CREATE OR REPLACE PACKAGE pkg AUTHID DEFINER AS
 
  TYPE rec IS RECORD (n1 NUMBER, n2 NUMBER);
 
  PROCEDURE p (x OUT rec, y NUMBER, z NUMBER);
END pkg;
/
CREATE OR REPLACE PACKAGE BODY pkg AS
 
  PROCEDURE p (x OUT rec, y NUMBER, z NUMBER) AS
  BEGIN
    x.n1 := y;
    x.n2 := z;
  END p;
END pkg;
/
DECLARE
  r       pkg.rec;
  dyn_str VARCHAR2(3000);
BEGIN
  dyn_str := 'BEGIN pkg.p(:x, 6, 8); END;';
 
  EXECUTE IMMEDIATE dyn_str USING OUT r;
 
  DBMS_OUTPUT.PUT_LINE('r.n1 = ' || r.n1);
  DBMS_OUTPUT.PUT_LINE('r.n2 = ' || r.n2);
END;
/

Example 7-4 Dynamically Invoking Subprogram with Assoc. Array Formal Parameter

CREATE OR REPLACE PACKAGE pkg AUTHID DEFINER AS
 
  TYPE number_names IS TABLE OF VARCHAR2(5)
    INDEX BY PLS_INTEGER;
 
  PROCEDURE print_number_names (x number_names);
END pkg;
/
CREATE OR REPLACE PACKAGE BODY pkg AS
  PROCEDURE print_number_names (x number_names) IS
  BEGIN
    FOR i IN x.FIRST .. x.LAST LOOP
      DBMS_OUTPUT.PUT_LINE(x(i));
    END LOOP;
  END;
END pkg;
/
DECLARE  
  digit_names  pkg.number_names;
  dyn_stmt     VARCHAR2(3000);
BEGIN
  digit_names(0) := 'zero';
  digit_names(1) := 'one';
  digit_names(2) := 'two';
  digit_names(3) := 'three';
  digit_names(4) := 'four';
  digit_names(5) := 'five';
  digit_names(6) := 'six';
  digit_names(7) := 'seven';
  digit_names(8) := 'eight';
  digit_names(9) := 'nine';
 
  dyn_stmt := 'BEGIN pkg.print_number_names(:x); END;';
  EXECUTE IMMEDIATE dyn_stmt USING digit_names;
END;
/

Example 7-5 Dynamically Invoking Subprogram with Nested Table Formal Parameter

CREATE OR REPLACE PACKAGE pkg AUTHID DEFINER AS
 
  TYPE names IS TABLE OF VARCHAR2(10);
 
  PROCEDURE print_names (x names);
END pkg;
/
CREATE OR REPLACE PACKAGE BODY pkg AS
  PROCEDURE print_names (x names) IS
  BEGIN
    FOR i IN x.FIRST .. x.LAST LOOP
      DBMS_OUTPUT.PUT_LINE(x(i));
    END LOOP;
  END;
END pkg;
/
DECLARE
  fruits   pkg.names;
  dyn_stmt VARCHAR2(3000);
BEGIN
  fruits := pkg.names('apple', 'banana', 'cherry');
  
  dyn_stmt := 'BEGIN pkg.print_names(:x); END;';
  EXECUTE IMMEDIATE dyn_stmt USING fruits;
END;
/

Example 7-6 Dynamically Invoking Subprogram with Varray Formal Parameter

CREATE OR REPLACE PACKAGE pkg AUTHID DEFINER AS
 
  TYPE foursome IS VARRAY(4) OF VARCHAR2(5);
 
  PROCEDURE print_foursome (x foursome);
END pkg;
/
CREATE OR REPLACE PACKAGE BODY pkg AS
  PROCEDURE print_foursome (x foursome) IS
  BEGIN
    IF x.COUNT = 0 THEN
      DBMS_OUTPUT.PUT_LINE('Empty');
    ELSE 
      FOR i IN x.FIRST .. x.LAST LOOP
        DBMS_OUTPUT.PUT_LINE(x(i));
      END LOOP;
    END IF;
  END;
END pkg;
/
DECLARE
  directions pkg.foursome;
  dyn_stmt VARCHAR2(3000);
BEGIN
  directions := pkg.foursome('north', 'south', 'east', 'west');
  
  dyn_stmt := 'BEGIN pkg.print_foursome(:x); END;';
  EXECUTE IMMEDIATE dyn_stmt USING directions;
END;
/

Example 7-7 Uninitialized Variable Represents NULL in USING Clause

CREATE TABLE employees_temp AS SELECT * FROM EMPLOYEES;

DECLARE
  a_null  CHAR(1);  -- Set to NULL automatically at run time
BEGIN
  EXECUTE IMMEDIATE 'UPDATE employees_temp SET commission_pct = :x'
    USING a_null;
END;
/

Example 7-8 Native Dynamic SQL with OPEN FOR, FETCH, and CLOSE Statements

DECLARE
  TYPE EmpCurTyp  IS REF CURSOR;
  v_emp_cursor    EmpCurTyp;
  emp_record      employees%ROWTYPE;
  v_stmt_str      VARCHAR2(200);
  v_e_job         employees.job%TYPE;
BEGIN
  -- Dynamic SQL statement with placeholder:
  v_stmt_str := 'SELECT * FROM employees WHERE job_id = :j';

  -- Open cursor & specify bind variable in USING clause:
  OPEN v_emp_cursor FOR v_stmt_str USING 'MANAGER';

  -- Fetch rows from result set one at a time:
  LOOP
    FETCH v_emp_cursor INTO emp_record;
    EXIT WHEN v_emp_cursor%NOTFOUND;
  END LOOP;

  -- Close cursor:
  CLOSE v_emp_cursor;
END;
/

Example 7-9 Querying a Collection with Native Dynamic SQL

CREATE OR REPLACE PACKAGE pkg AUTHID DEFINER AS
  TYPE rec IS RECORD(f1 NUMBER, f2 VARCHAR2(30));
  TYPE mytab IS TABLE OF rec INDEX BY pls_integer;
END;
/

DECLARE
  v1 pkg.mytab;  -- collection of records
  v2 pkg.rec;
  c1 SYS_REFCURSOR;
BEGIN
  OPEN c1 FOR 'SELECT * FROM TABLE(:1)' USING v1;
  FETCH c1 INTO v2;
  CLOSE c1;
  DBMS_OUTPUT.PUT_LINE('Values in record are ' || v2.f1 || ' and ' || v2.f2);
END;
/

Example 7-11 DBMS_SQL.RETURN_RESULT Procedure

CREATE OR REPLACE PROCEDURE p AUTHID DEFINER AS
  c1 SYS_REFCURSOR;
  c2 SYS_REFCURSOR;
BEGIN
  OPEN c1 FOR
    SELECT first_name, last_name
    FROM employees
    WHERE employee_id = 176;
 
  DBMS_SQL.RETURN_RESULT (c1);
  -- Now p cannot access the result.
 
  OPEN c2 FOR
    SELECT city, state_province
    FROM locations
    WHERE country_id = 'AU';
 
  DBMS_SQL.RETURN_RESULT (c2);
  -- Now p cannot access the result.
END;
/
BEGIN
  p;
END;
/

Result:

ResultSet #1

FIRST_NAME           LAST_NAME
-------------------- -------------------------
Jonathon             Taylor

ResultSet #2

CITY                           STATE_PROVINCE
------------------------------ -------------------------
Sydney                         New South Wales

Example 7-12 DBMS_SQL.GET_NEXT_RESULT Procedure

CREATE OR REPLACE PROCEDURE get_employee_info (id IN VARCHAR2) AUTHID DEFINER AS
  rc  SYS_REFCURSOR;
BEGIN
  -- Return employee info
 
  OPEN rc FOR SELECT first_name, last_name, email, phone_number
              FROM employees
              WHERE employee_id = id;
  DBMS_SQL.RETURN_RESULT(rc);
 
  -- Return employee job history
 
  OPEN RC FOR SELECT job_title, start_date, end_date
              FROM job_history jh, jobs j
              WHERE jh.employee_id = id AND
                    jh.job_id = j.job_id
              ORDER BY start_date DESC;
  DBMS_SQL.RETURN_RESULT(rc);
END;
/
<<main>>
DECLARE
  c            INTEGER;
  rc           SYS_REFCURSOR;
  n            NUMBER;
 
  first_name   VARCHAR2(20);
  last_name    VARCHAR2(25);
  email        VARCHAR2(25);
  phone_number VARCHAR2(20);
 
  job_title    VARCHAR2(35);
  start_date   DATE;
  end_date     DATE;
 
BEGIN
 
  c := DBMS_SQL.OPEN_CURSOR(true);
  DBMS_SQL.PARSE(c, 'BEGIN get_employee_info(:id); END;', DBMS_SQL.NATIVE);
  DBMS_SQL.BIND_VARIABLE(c, ':id', 176);
  n := DBMS_SQL.EXECUTE(c);
 
  -- Get employee info
 
  dbms_sql.get_next_result(c, rc);
  FETCH rc INTO first_name, last_name, email, phone_number;
 
  DBMS_OUTPUT.PUT_LINE('Employee: '||first_name || ' ' || last_name);
  DBMS_OUTPUT.PUT_LINE('Email: ' ||email);
  DBMS_OUTPUT.PUT_LINE('Phone: ' ||phone_number);
 
  -- Get employee job history
 
  DBMS_OUTPUT.PUT_LINE('Titles:');
  DBMS_SQL.GET_NEXT_RESULT(c, rc);
  LOOP
    FETCH rc INTO job_title, start_date, end_date;
    EXIT WHEN rc%NOTFOUND;
    DBMS_OUTPUT.PUT_LINE
      ('- '||job_title||' ('||start_date||' - ' ||end_date||')');
  END LOOP;
 
  DBMS_SQL.CLOSE_CURSOR(c);
END main;
/

Result:

Employee: Jonathon Taylor
Email: JTAYLOR
Phone: 011.44.1644.429265
Titles:
- Sales Manager (01-JAN-07 - 31-DEC-07)
- Sales Representative (24-MAR-06 - 31-DEC-06)
 
PL/SQL procedure successfully completed.

Example 7-13 Switching from DBMS_SQL Package to Native Dynamic SQL

CREATE OR REPLACE TYPE vc_array IS TABLE OF VARCHAR2(200);
/
CREATE OR REPLACE TYPE numlist IS TABLE OF NUMBER;
/
CREATE OR REPLACE PROCEDURE do_query_1 (
  placeholder vc_array,
  bindvars vc_array,
  sql_stmt VARCHAR2
) AUTHID DEFINER
IS
  TYPE curtype IS REF CURSOR;
  src_cur     curtype;
  curid       NUMBER;
  bindnames   vc_array;
  empnos      numlist;
  depts       numlist;
  ret         NUMBER;
  isopen      BOOLEAN;
BEGIN
  -- Open SQL cursor number:
  curid := DBMS_SQL.OPEN_CURSOR;

  -- Parse SQL cursor number:
  DBMS_SQL.PARSE(curid, sql_stmt, DBMS_SQL.NATIVE);

  bindnames := placeholder;

  -- Bind variables:
  FOR i IN 1 .. bindnames.COUNT LOOP
    DBMS_SQL.BIND_VARIABLE(curid, bindnames(i), bindvars(i));
  END LOOP;

  -- Run SQL cursor number:
  ret := DBMS_SQL.EXECUTE(curid);

  -- Switch from DBMS_SQL to native dynamic SQL:
  src_cur := DBMS_SQL.TO_REFCURSOR(curid);
  FETCH src_cur BULK COLLECT INTO empnos, depts;

  -- This would cause an error because curid was converted to a REF CURSOR:
  -- isopen := DBMS_SQL.IS_OPEN(curid);

  CLOSE src_cur;
END;
/

Example 7-14 Switching from Native Dynamic SQL to DBMS_SQL Package

CREATE OR REPLACE PROCEDURE do_query_2 (
  sql_stmt VARCHAR2
) AUTHID DEFINER
IS
  TYPE curtype IS REF CURSOR;
  src_cur   curtype;
  curid     NUMBER;
  desctab   DBMS_SQL.DESC_TAB;
  colcnt    NUMBER;
  namevar   VARCHAR2(50);
  numvar    NUMBER;
  datevar   DATE;
  empno     NUMBER := 100;
BEGIN
  -- sql_stmt := SELECT ... FROM employees WHERE employee_id = :b1';

  -- Open REF CURSOR variable:
  OPEN src_cur FOR sql_stmt USING empno;

  -- Switch from native dynamic SQL to DBMS_SQL package:
  curid := DBMS_SQL.TO_CURSOR_NUMBER(src_cur);
  DBMS_SQL.DESCRIBE_COLUMNS(curid, colcnt, desctab);

  -- Define columns:
  FOR i IN 1 .. colcnt LOOP
    IF desctab(i).col_type = 2 THEN
      DBMS_SQL.DEFINE_COLUMN(curid, i, numvar);
    ELSIF desctab(i).col_type = 12 THEN
      DBMS_SQL.DEFINE_COLUMN(curid, i, datevar);
      -- statements
    ELSE
      DBMS_SQL.DEFINE_COLUMN(curid, i, namevar, 50);
    END IF;
  END LOOP;

  -- Fetch rows with DBMS_SQL package:
  WHILE DBMS_SQL.FETCH_ROWS(curid) > 0 LOOP
    FOR i IN 1 .. colcnt LOOP
      IF (desctab(i).col_type = 1) THEN
        DBMS_SQL.COLUMN_VALUE(curid, i, namevar);
      ELSIF (desctab(i).col_type = 2) THEN
        DBMS_SQL.COLUMN_VALUE(curid, i, numvar);
      ELSIF (desctab(i).col_type = 12) THEN
        DBMS_SQL.COLUMN_VALUE(curid, i, datevar);
        -- statements
      END IF;
    END LOOP;
  END LOOP;

  DBMS_SQL.CLOSE_CURSOR(curid);
END;
/