Using COUNT with DISTINCT to get more information

SELECT COUNT(DISTINCT vendor_id) AS number_of_vendors,

COUNT(vendor_id) AS number_of_invoices,

ROUND(AVG(invoice_total), 2) AS avg_invoice_amt,

SUM(invoice_total) AS total_invoice_amt

FROM invoices

WHERE invoice_date > '2018-01-01'

In this example I want to know more than just how many unpaid bills I owe, I also want to know how many vendors I am dealing with

By Adding DISTINCT here I will get the number of Vendors who have invoices in the invoice table

The Output for this Query