20. List the balances of customers who have madepurchases during the current invoice cycle—that is, for thecustomers who appear in the INVOICE table. The results of thisquery are shown in Figure P7.20, sorted by customercode.
FIGURE P7.9 THE CH07 SALECO DATABASE Relational diagram CUSTOMER VENDOR INVOICE PK,FK1 FK1 Cus Code Inv Date FK2
OR
OR