SQL> DECLARE
  2    qry        VARCHAR2(1000);
  3    vout       VARCHAR2(100);
  4  BEGIN
  5    qry :=  'WITH ' ||
  6            'data AS ' ||
  7            '(SELECT column_1, column_2 FROM tnum ' ||
  8            'WHERE column_3 = :C3) ' ||
  9            'SELECT column_1 FROM data WHERE column_2 = :C2';
 10    EXECUTE IMMEDIATE qry INTO vout USING '200', 'ghi';
 11    dbms_output.put_line('Output: '||vout);
 12  END;
 13  /
Output: 4

PL/SQL procedure successfully completed.

SQL> 
SQL> DECLARE
  2    qry        VARCHAR2(1000);
  3    vout       VARCHAR2(100);
  4  BEGIN
  5    qry :=  'WITH ' ||
  6            'data AS ' ||
  7            '(SELECT column_1, column_2 FROM tnum ' ||
  8            'WHERE column_3 = :C3 AND column_2 = :C2) ' ||
  9            'SELECT column_1 FROM data WHERE column_2 = :C2';
 10  
 11    EXECUTE IMMEDIATE qry INTO vout USING '200', 'ghi';
 12    dbms_output.put_line('Output: '||vout);
 13  END;
 14  /
DECLARE
*
ERROR at line 1:
ORA-01008: not all variables bound
ORA-06512: at line 11


SQL> 
SQL> DECLARE
  2    qry        VARCHAR2(1000);
  3    vout       VARCHAR2(100);
  4  BEGIN
  5    qry :=  'WITH ' ||
  6            'data AS ' ||
  7            '(SELECT column_1, column_2 FROM tnum ' ||
  8            'WHERE column_3 = :C3 AND column_2 = :C2) ' ||
  9            'SELECT column_1 FROM data WHERE column_2 = :C2';
 10  
 11    EXECUTE IMMEDIATE qry INTO vout USING '200', 'ghi', 'ghi';
 12    dbms_output.put_line('Output: '||vout);
 13  END;
 14  /
Output: 4

PL/SQL procedure successfully completed.

 'WHERE column_3 = :C3 AND column_2 = :C2) ' ||
  9            'SELECT column_1 FROM data WHERE column_2 = :C2';

EXECUTE IMMEDIATE qry INTO vout USING '200', 'ghi', 'ghi';

DECLARE
  p_empno  INTEGER;
  p_deptno INTEGER;
  str      VARCHAR2(400);
  l_ename  VARCHAR2(30);
BEGIN
  p_empno :=7839;
  p_deptno:=10;
  str     :='select ename from emp 
              where empno=:p_empno and deptno=:p_deptno 
              and exists (select null from dept where dept.deptno=emp.deptno and dept.deptno=:p_deptno)';
  EXECUTE immediate str INTO l_ename USING p_empno,p_deptno;
end;

ORA-01008: not all variables bound
ORA-06512: at line 10
01008. 00000 -  "not all variables bound"
*Cause:    
*Action:

EXECUTE immediate str INTO l_ename USING p_empno,p_deptno,p_deptno;

in sql
sql_stmt := 'INSERT INTO payroll VALUES (:x, :x, :y, :x)';
   execute immediate sql_stmt using a, a, b, a;
   
in Pl/sql   
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;  -- calc_stats(a, a, b, a)
end;

DECLARE
  p_empno  INTEGER;
  p_deptno INTEGER;
  str      VARCHAR2(400);
  l_ename  VARCHAR2(30);
BEGIN
  p_empno :=7839;
  p_deptno:=10;
  str     :='select ename from emp 
              where empno=:p_empno and deptno=:p_deptno 
              and exists (select null from dept where dept.deptno=emp.deptno and dept.deptno=:p_deptno)';
  execute immediate str into l_ename using p_empno,p_deptno,p_deptno;-- a,b,b
  dbms_output.put_line(str);
end;