DECLARE
  l_Raw     VARCHAR2(4000) := 'something';
  l_Cleaned VARCHAR2(4000);
BEGIN
  EXECUTE IMMEDIATE "BEGIN :1 := REGEXP_REPLACE( :2, '[^ 0-9A-Za-z]', ''); END;"
    USING l_Cleaned, l_Raw;
  -- Do something with l_cleaned
END;
/

失败是因为双引号用于标识符，而你需要单引号，这是字符串文字（并转义字符串中的单引号），并且因为你没有声明OUT绑定变量：

DECLARE
  l_Raw     VARCHAR2(4000) := 'something';
  l_Cleaned VARCHAR2(4000);
BEGIN
  EXECUTE IMMEDIATE 'BEGIN :1 := REGEXP_REPLACE( :2, ''[^ 0-9A-Za-z]'', ''''); END;'
    USING OUT l_Cleaned, l_Raw;
  -- Do something with l_cleaned
END;
/

但是，你可以只使用PL/SQL匿名块而不使用EXECUTE IMMEDIATE，因为你试图执行的东西没有任何动态：

DECLARE
  l_Raw     VARCHAR2(4000) := 'something';
  l_Cleaned VARCHAR2(4000);
BEGIN
  l_Cleaned := REGEXP_REPLACE( l_raw, '[^ 0-9A-Za-z]');
  -- Do something with l_cleaned
END;
/

Execute immediate需要PL/SQL;你不能只是“执行”它（例如在SQL级别）。
这里有个例子看看有没有用

SQL> set serveroutput on
SQL>
SQL> declare
  2    l_input  varchar2(20) := 'L#it%/lef"oot';
  3    l_result varchar2(20);
  4  begin
  5    execute immediate q'{select regexp_replace(:b, '[^ 0-9A-Za-z]', '') from dual}'
  6      into l_result using l_input;
  7
  8    dbms_output.put_line('Result = ' || l_result);
  9  end;
 10  /
Result = Litlefoot

PL/SQL procedure successfully completed.

SQL>

或者，在SQL*Plus中运行另一个选项：

SQL> var b varchar2(20)
SQL> exec :b := 'L#it%/lef"oot';

PL/SQL procedure successfully completed.

SQL> var result varchar2(20)
SQL> exec :result := regexp_replace(:b, '[^ 0-9A-Za-z]', '');

PL/SQL procedure successfully completed.

SQL> print result

RESULT
--------------------------------
Litlefoot

SQL>