Question

I have two tables like these

Invoice   (invoice_no, invoice_date, customer_id, ...),  
Customers (customer_id, customer_name, ...)

Now what I want to do is list invoices ordered by customer name.

SELECT b.customer_name, a.*
FROM Invoice a, Customers b
WHERE a.customer_id=b.customer_id
ORDER BY b.customer_name

but problem with this sql is that if there are invoices without customer_id,
how can I list those invoices first and invoices with customer_id by customer_name asc.

Answer 1

use LEFT JOIN instead.

“kinda” weird. How come there are some invoices that without customer? To whom are you issuing it? Anyway, here’s the query.

SELECT  a.*, b.*  // SELECT only the columns you want
FROM    Invoice a
        LEFT JOIN Customers b
            ON a.customer_ID = b.customer_ID

To fully gain knowledge about joins, kindly visit the link below:

• Visual Representation of SQL Joins