USE myDB
      GO

      IF EXISTS(
          SELECT  *
          FROM    sys.triggers
          WHERE   name = N'table_alter_drop_safety'
          AND     parent_class_desc = N'DATABASE'
      )
      DROP TRIGGER table_alter_drop_safety ON DATABASE
      GO

      CREATE TRIGGER table_alter_drop_safety ON DATABASE
          FOR DROP_TABLE, ALTER_TABLE
      AS
          IF IS_MEMBER ('db_owner') = 0
      BEGIN
          PRINT 'You must ask your DBA to drop or alter tables!'
          ROLLBACK TRANSACTION
      END
      GO