???SQL?????????

????5??????????????

?????????????ж??tb_emp???￡???????????μ?sal?У???????USING NULL????????????

DECLARE
         sql_stmt VARCHAR2(100);
         v_empno  NUMBER := 7900;
       BEGIN
         sql_stmt := 'UPDATE tb_emp SET sal = :new_sal WHERE empno=:eno';
         EXECUTE IMMEDIATE sql_stmt
           USING NULL??v_empno;     --?????????????NULL
       END;
 
           USING NULL??v_empno;
                *
       ERROR at line 7:
       ORA-06550: line 7?? column 11:
       PLS-00457: expressions have to be of SQL types
       ORA-06550: line 6?? column 3:
       PL/SQL: Statement ignored

?????????????

DECLARE
             sql_stmt VARCHAR2(100);
             v_empno  NUMBER := 7900;
             v_sal    NUMBER;    --????????±????????????
           BEGIN
             sql_stmt := 'UPDATE tb_emp SET sal = :new_sal WHERE empno=:eno';
             EXECUTE IMMEDIATE sql_stmt
              USING v_sal?? v_empno;
             COMMIT;
             DBMS_OUTPUT.PUT_LINE('The new sal is NULL');
           END;

????6??????????????????????

???????USING????????????SQL?????INTO??????????????????????????????д???

??????????????????v_ename??v_sal????????????????????INTO???С?????????????′??????????????????????????????????????????????????д????????

DECLARE
             TYPE emp_cur_type IS REF CURSOR;
             emp_cv   emp_cur_type;
             sql_stat VARCHAR2(100);
             v_dno    NUMBER := &dno;
             v_ename  VARCHAR2(25);
             v_sal    NUMBER;
 
           BEGIN
             sql_stat := 'SELECT ename??sal FROM scott.emp WHERE deptno = :dno';
             OPEN emp_cv FOR sql_stat     --????α?????????SQL
              USING v_dno;
             LOOP
              FETCH emp_cv
                INTO v_sal?? v_ename;     --?????????????????????????
              EXIT WHEN emp_cv%NOTFOUND;
              dbms_output.put_line('Employee name is ??' || v_ename ||
                                 '??  The sal is ??' || v_sal);
             END LOOP;
             CLOSE emp_cv;
           END;
 
           Enter value for dno: 20
           old   5:   v_dno    NUMBER := &dno;
           new   5:   v_dno    NUMBER := 20;
           DECLARE
           *
           ERROR at line 1:
           ORA-01722: invalid number
           ORA-06512: at line 14

?????????

?????????????????????