通过Database Link集成远程数据库时，从远程数据库上查询Blob字段时总返回ORA- 22992 错误 。有人采用物化视图解决这个问题，但物化视图同步机制会带来麻烦，如果同步时间设置过短，则占用大量的系统资源，给服务器带来极大的压力；如果设置时间过长，前台用户不可接受。

参考网上资料，据说来自 AskTom，使用全局临时表，实现了自认为优雅的解决。

代码如下：

create or replace package pkg_photo as

type sys_refcursor is ref cursor;

procedure proc_photo(p_sfzh in string,

p_photo OUT pkg_rkzp.sys_refcursor);

end pkg_photo;

create or replace package body pkg_photo as

procedure proc_photo(p_sfzh in string, p_photo OUT pkg_rkzp.sys_refcursor)

AS

v_num number;

v_sql varchar2(2000);

v_sfzh string(18);

BEGIN

select count(*) into v_num from user_tables where table_name=upper('tmp_jn_czrk_zp');

dbms_output.PUT_LINE(v_num);

if v_num<1 then

v_sql := 'create global temporary table tmp_ryzp(sfzh char(18),photo blob) on commit preserve rows';

EXECUTE IMMEDIATE v_sql;

end if;

v_sql := 'insert into tmp_photo select sfzh,photo from v_remote_table@mydblink where sfzh=:1';

EXECUTE IMMEDIATE v_sql using p_sfzh;

OPEN p_photo FOR v_sql;

EXCEPTION

WHEN NO_DATA_FOUND

THEN NULL;

WHEN OTHERS

THEN RAISE;

END proc_photo;

end pkg_photo;