title: how i can to make the count to get the amount of something
body: <p>I have this attributes in my table(Invoices):
  CustomerID, InvoiceID</p>
  
  <p>Now i'm try to show the amount of Invoices of every CustomerID, i'm using GROUP BY and count but it's doesn't work.</p>
  
  <pre><code>select customerID ,count(invoiceID) as amountOfinvoices
  FROM Invoices
  group by customerID,invoiceID
  </code></pre>