如何在以下过程中正确引用数据库 link 名称

Question

我在另一个论坛上问过一个类似的问题，但我没有完全理解上下文，所以我创建了一个更好的例子。有谁知道我如何在这里正确引用 link ？如果您对数据库进行硬编码，代码会将 .csv 文件发送到相关目录 link，但我想将其传递到变量中。

CREATE OR REPLACE PROCEDURE WRITE_EST_SIZE
IS
   file_handle   UTL_FILE.file_type;
   v_link_name   VARCHAR2 (10);
   v_csv_name    VARCHAR2 (40);
BEGIN
   v_csv_name := 'file_name';

   --Table contains the name of the database link
   SELECT link_name INTO v_link_name FROM link_name;

   file_handle :=
      UTL_FILE.fopen ('ESTIMATES_CSV',
                      v_csv_name || '.csv',
                      'w',
                      32767);
   UTL_FILE.put_line (file_handle,
                      'OWNER,SEGMENT_NAME,SEGMENT_TYPE,SUM_BYTES');

   FOR rws
      IN (  SELECT s.owner,
                   s.segment_name,
                   'T' AS FLAG,
                   SUM (s.bytes) / 1024 / 1024 AS SUM_BYTES
              FROM DBA_SEGMENTS@LINK_TO_DEV s
             --Actually, I want THIS below to work
             --from DBA_SEGMENTS@v_link_name s
             WHERE     s.owner =
                          (SELECT DISTINCT schema_name FROM target_schema)
                   AND s.segment_name IN (SELECT table_name FROM ref_table)
                   AND s.segment_type LIKE '%TABLE%'
          GROUP BY s.owner, s.segment_name)
   LOOP
      UTL_FILE.put_line (
         file_handle,
            rws.OWNER
         || ','
         || rws.SEGMENT_NAME
         || ','
         || rws.FLAG
         || ','
         || rws.SUM_BYTES);
   END LOOP;

   UTL_FILE.fclose (file_handle);
END WRITE_EST_SIZE;
/

Answer 1

一种选择是使用动态 SQL。如果是简单，没问题，但是- 动态游标FOR循环？不，谢谢。

另一种选择是创建一个视图作为 UNION 选择您可能正在使用的所有数据库链接，例如

create or replace view v_dba_segments as
  select 'db_link_1' link, s.owner, s.segment_name, ...
  from dba_segments@db_link_1
  union all
  select 'db_link_2' link, s.owner, s.segment_name, ...
  from dba_segments@db_link_2
  union all 
  ...

然后您将在上述过程中将其引用为

for rws in (select owner, segment_name, ...
            from v_dba_segments             --> view
            where link = v_link_name        --> this is where your variable comes into the game
              and ...
           )
loop
   ...
end loop;

如何在以下过程中正确引用数据库 link 名称

How can I properly reference the database link name in the below procedure

oracle

plsql

dblink

procedure