How to select rows where multiple joined table values meet selection criteria?

Question

Given the following sample table schema

Customer Table

CustID
1
2
3

Invoice Table

CustID InvoiceID

1       10
1            


        

Answer 1

The Group By answers will work unless it is possible for there to be multiples of CustID/InvoiceId in the Invoice table. Then you might get some unexpected results. I like the answer below a little better because it mirrors more closely the logic as you are describing it.

Select CustID
From Customer
Where
  Exists (Select 1 from Invoice Where CustID=Customer.CustID and InvoiceID=10)
and
  Exists (Select 1 from Invoice Where CustID=Customer.CustID and InvoiceID=20)