Dynamic Query Error in PLSQL

Question

I am trying to execute this procedure:

CREATE OR REPLACE PROCEDURE SP_DYNAMIC 
AS
  tbl_list VARCHAR2(2000);
  DBLINK   VARCHAR2(100);
  V_SQL    VARCHAR2(1000);
BEGIN
  DBLINK := 'SOME_LINK';
  V_SQL := 'SELECT table_name,table_owner FROM dba_tab_modifications@:DB_LINK';

  EXECUTE IMMEDIATE V_SQL USING DBLINK;

  COMMIT;

  Dbms_Output.PUT_LINE (TBL_LIST);
END;

But When I execute the stored procedure I get the error:

ORA-01729: database link name expected
ORA-06512: at "SYSTEM.SP_DYNAMIC"
ORA-06512: at line 2

Can somebody help me with what I am doing wrong here?

Answer 1

The reason it doesn't work is because you can't use a bind variable as the dblink. You get the same error when running the following:

select * from dual@:dblink;

If you absolutely must use dynamic sql, you'd have to concatenate the dblink name into the statement - but you'll have to be aware that you're now open to SQL Injection:

V_SQL := 'SELECT table_name,table_owner FROM dba_tab_modifications@'||DB_LINK;