I have a table slot which has a start\_time and end\_time. I want no other slot to be created having the same start and end time. A unique constraint as shown in the schema below

```
CREATE TABLE slot(
id SERIAL PRIMARY KEY,
start_time TIMETZ NOT NULL,
end_time TIMETZ NOT NULL,
CONSTRAINT slot_start_end_unique UNIQUE (start_time,end_time)  
);

```

can be easily bypassed by picking up one minute + or - time. I want to add a constraint so that no equivalent time slot can be created or a subset time slot cannot be created.
I am thinking of using `check` to prevent any practically same slot from being created.
Can anyone please point towards the right direction?