动态 SQL/异常处理 -00942 - Oracle PL/SQL

Question

最初我试图创建一个异常来捕获一个不存在的表 (-00942)。根据 Alex 和 Raj 的反馈，我修改了代码以使用 EXECUTE IMMEDIATE。这有助于识别表，但是当我将表从“员工”更正为“员工”时，这是我数据库中存在的表，我本来希望代码运行时不会出错，就像我没有使用 EXECUTE IMMEDIATE 一样.

使用 EXECUTE IMMEDIATE 时，代码是否可以无异常地运行，而不是生成 catch all 异常？

EXECUTE IMMEDIATE 'SELECT last_name INTO v_name FROM Employees WHEREsalary = v_sal';

WHEN OTHERS THEN :g_message := '发生了其他一些错误。';

我希望代码能够无一例外地运行。

VARIABLE g_message VARCHAR2(250)

DEFINE p_sal = 12000

DECLARE 
   v_name employees.last_name%TYPE;
   v_sal employees.salary%TYPE := &p_sal;

   table_does_not_exist exception;  
   PRAGMA EXCEPTION_INIT(table_does_not_exist, -942);

BEGIN

   EXECUTE IMMEDIATE
   'SELECT last_name INTO v_name FROM employees WHERE salary = v_sal';

   DBMS_OUTPUT.put_line(v_name);


 EXCEPTION 

   WHEN table_does_not_exist then 
   :g_message := 'table dose not exist';  


   WHEN NO_DATA_FOUND THEN 
   :g_message := 'No employee with a salary of '||TO_CHAR(v_sal);  

   WHEN OTHERS THEN
   :g_message := 'Some other error occurred.';
 END;
 /
 PRINT g_message

Answer 1

试试下面：

DECLARE 
   v_name employee.emp_name%TYPE;
   v_sal employee.emp_sal%TYPE := 12000;

   table_does_not_exist exception;  
   PRAGMA EXCEPTION_INIT(table_does_not_exist, -942);

BEGIN

execute immediate
   'SELECT emp_name        
   FROM employee_l
   WHERE emp_sal = v_sal' INTO v_name;

   DBMS_OUTPUT.put_line(v_name);


 EXCEPTION 

   WHEN table_does_not_exist then 
   dbms_output.put_line( 'table dose not exist');  


   WHEN NO_DATA_FOUND THEN 
   dbms_output.put_line(  'No employee with a salary of '||TO_CHAR(v_sal));  

   WHEN OTHERS THEN
   dbms_output.put_line( 'Some other error occurred.');
 END;
 /