Question

Okay hello there I have 2 tables

Route table which has

route ID, frequency, start destination, final destination

and

Operates table which has

Proportion, Operator name, Route ID

I need to select Route id and frequency where the operator name is Arriva.

I put this SQL together which works and gets me the result but I am not sure if this is the correct way of doing it.

SELECT route_number, frequency
FROM route, operates
WHERE route_ID = route_number
AND operator_name =  'Arriva'

Answer 1

It is the right way, just that your first where statement is wrong:

SELECT route_number, frequency
FROM route, operates
WHERE route_ID = **route_number**
AND operator_name =  'Arriva'

It should be route_ID as well (at least from what you said). In order for this to work you need to give names to your tables, so SQL knows which columns you are comparing (since the names are the same from both tables). Like this:

SELECT 
    route_number, 
    frequency
FROM 
    route r, 
    operates o
WHERE 
    r.route_ID = o.route_number
    AND o.operator_name =  'Arriva'