Question

I need to ensure that tables are not dropped from my database. Should I..
Create DDL(or DML ?) trigger that contains COMMIT or create DDL (or DML ?) trigger that contains ROLLBACK ?

Answer 1

Assuming SQL Server there is an example of doing this in BOL

CREATE TRIGGER safety 
ON DATABASE 
FOR DROP_TABLE, ALTER_TABLE 
AS 
   PRINT 'You must disable Trigger "safety" to drop or alter tables!' 
   ROLLBACK
;

You would be better off removing permissions from anyone that might DROP the tables inappropriately however. DDL triggers are after triggers, not instead of triggers so a drop table statement might still cause problems even if eventually rolled back.