Question

Regarding the difference between…

select * from table_a where id != 30 and name != 'Kevin';

and

select * from table_a where id != 30 or name != 'Kevin';

First one means, "select all rows from table_a where the id is not 30 and the name is not Kevin".

So {Id, Name} row of {30, ‘Bill’} would be returned from this first query.

But, the second one means, "select all rows from table_a where the id is not 30 or the name is not 'Kevin'".

So the above {30, ‘Bill’} would not be returned from this second query.

Is that right?

Answer 1

select * from table_a where id != 30 and name != 'Kevin';

So {Id, Name} row of {30, ‘Bill’} would be returned from this first
query.

No, it wouldn’t.

select * from table_a where id != 30 or name != 'Kevin';

So the above {30, ‘Bill’} would not be returned from this second
query.

No, it would. You have the logic backwards. Just try it.