Just to clarify,
in other words let say for example, we have this statement DELETE from Students where CalssName = 'Algebra'
would like to remove all other than algebra so inthis case we can change it to
DELETE from Students where CalssName <> 'Algebra'
but in the above example (first post) we have multiple conditions with OR clause so checking to see if i can use NOT () for whole where clause ? or not exists can you please provide some example if it is with not exists