Question

I have to get data from two SQL tables but I am unsure of what join to use and the same tables have the same customers_id table would I use an inner join?

table - customers

customers_id
customers_firstname
customers_lastname
customers_email_address

table - orders


customers_id
customers_street_address
customers_suburb
customers_city
customers_postcode
customers_state
customers_country

Answer 1

It depends on what results you want. If you want every record in Customers regardless of whether there is a matching record in orders the you would use an LEFT OUTER JOIN. If not you would use an INNER JOIN. This is the article I typically refer people to for a basic explanation of joins.

An INNER JOIN would look like this:

SELECT c.customers_id, 
       c.customers_firstname, 
       c.customers_lastname, 
       o.customers_street_address,
       o.customers_city,
       o.customers_postcode,
       o.customers_state
FROM customers as c
INNER JOIN orders as o
ON c.customers_id = o.customers_id

I purposely did not do select *. Try to get into the habit of only selecting the columns you want from tables instead of everything.