Delete From More than 1 table without using execute immediate

Question

Hi,
Am new to PL/SQL, I had been asked to delete few of the table for my ETL jobs in Oracle 10G R2. I have to delete(truncate) few tables and the table names are in another table with a flag to delete it or not. So, when ever I run the job it should check for the flag and for those flag which is 'Y' then for all those tables should be deleted without using the Execute Immediate, because I dont have privilages to use "Execute Immediate" statement.
Can anyone help me in how to do this.
Regards
Senthil

Answer 1

Then tell you DBA's, or better yet their boss, that they need some additional training in how Oracle actually works.
Yes, dynamic sql can be a bad thing when it is used to generate hundreds of identical queries that differ ony in the literals used in predicates, but for something like a set of delte table statements or truncate table statements, dynamic sql is no different in terms of the effect on the shared pool that hard coding the sql statements.
This is a bad use of dynamic sql, because it generates a lot of nearly identical statements due to the lack of bind variables. It is the type of thing your DBA's should, correctly, bring out the lead pipe for.
DECLARE
   l_sql VARCHAR2(4000);
BEGIN
   FOR r in (SELECT account_no FROM accounts_to_delete) LOOP
      l_sql := 'DELETE FROM accounts WHERE account_no = '||r.account_no;
      EXECUTE IMMEDIATE l_sql;
   END LOOP;
END;This will result in one sql statement in the shared pool for every row in accounts_to_delete. Although there is much else wrong with this example, from the bind variable perspective it should be re-written to use bind variables like:
DECLARE
   l_sql  VARCHAR2(4000);
   l_acct NUMBER;
BEGIN
   FOR r in (SELECT account_no FROM accounts_to_delete) LOOP
      l_sql := 'DELETE FROM accounts WHERE account_no = :b1';
      EXECUTE IMMEDIATE l_sql USING l_acct;
   END LOOP;
END;However, since you cannot bind object names into sql statements, the difference in terms of the number of statements that end up in the shared pool between this:
DECLARE
   l_sql VARCHAR2(4000);
BEGIN
   FOR r in (SELECT table_name, delete_tab, trunc_tab
             FROM tables_to_delete) LOOP
      IF r.delete_tab = 'Y' THEN
         l_sql := 'DELETE FROM '||r.table_name;
      ELSIF r.trunc_tab = 'Y' THEN
         l_sql := 'TRUNCATE TABLE '||r.table_name;
      ELSE
         l_sql := NULL;
      END IF;
      EXECUTE IMMEDIATE l_sql;
   END LOOP;
END;and something like this:
BEGIN
   DELETE FROM tab1;
   DELETE FROM tab2;
   EXECUTE IMMEDIATE 'TRUNCTE TABLE tab3';
END;or this as a sql script
DELETE FROM tab1;
DELETE FROM tab2;
TRUNCTE TABLE tab3;is absolutley nothing.
Note that if you are truncating some of the tables, and wnat/need to use a stored procedure, you are going to have to use dynamic sql for the truncates anyway since trncate is ddl, and you cannot do ddl in pl/sql wiothout using dynamic sql.
John