Question

I am hoping someone will be able to point me in the right direction.

I have a COUNTRY table, containing a primary ID, and country name (e.g. France)

I have a second table PAYMETHODS_COUNTRIES, which contains a primary id, payment method id (e.g. 4) and country id

I am trying to output a list of checkboxes on each payment method, to control which countries (or users in which countries) have access to those local payment methods.

I have the checkbox list working okay, and the processing of the form is also working. The last remaining thing, is to output the list of country checkboxes with selected countries (e.g. this payment method is available in France and Germany) shown as CHECKED.

So what I am trying to do is to output a complete list of all countries

SELECT id, name FROM country ORDER BY id ASC

And then include the PAYMETHODS_COUNTRIES table something like this (not working of course)

SELECT country.id AS countryid,
country.name AS countryname,
paymethods_countries.id AS methodid
FROM country LEFT JOIN `paymethods_countries` 
ON country.id = paymethods_countries.country
WHERE paymethods_countries.paymethod = 10

This example query only shows rows that actually have a record in PAYMETHODS_COUNTRIES, not what I am after.

What I was hoping for, is a complete list of country.id + country.name, with a final field (the ID of the PAYMETHODS_COUNTRIES table) – which should be null where there is no link. That way I should be able to check for null or otherwise, and output CHECKED for those rows.

Hopefully that makes sense – or if anyone knows a better way to achieve what I am doing, your thoughts are appreciated.

Answer 1

While the other answer here will produce the desired result, semantically it is more correct to move the condition from the WHERE clause to the ON clause:

SELECT country.id AS countryid,
    country.name AS countryname,
    paymethods_countries.id AS methodid
FROM country 
LEFT JOIN `paymethods_countries` 
   ON country.id = paymethods_countries.country and paymethods_countries.paymethod = 10

This eliminates the need to add the extra OR condition in the WHERE clause.