placeholders with DY_SQL

To call the procedure from a dynamic PL/SQL block, you must specify the IN OUT
mode for the bind argument associated with formal parameter deptid, as shown in
Example 7–3 Using IN OUT Bind Arguments to Specify Substitutions
===================================================================================
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
plsql_block := 'BEGIN create_dept(:a, :b, :c, :d); END;';
EXECUTE IMMEDIATE plsql_block
USING IN OUT new_deptid, new_dname, new_mgrid, new_locid;
END;
================================================================================

CREATE PROCEDURE calc_stats(w NUMBER, x NUMBER, y NUMBER, z NUMBER) IS
BEGIN
DBMS_OUTPUT.PUT_LINE(w + x + y + z);
END;
/
DECLARE
a NUMBER := 4;
b NUMBER := 7;
plsql_block VARCHAR2(100);
BEGIN
plsql_block := 'BEGIN calc_stats(:x, :x, :y, :x); END;';
EXECUTE IMMEDIATE plsql_block USING a, b;
END;
/============================================================