Question

Which of the following statements best describes what this update statement does?

UPDATE invoicesSET credit_total = invoice_total - payment_totalWHERE vendor_id = 10 AND invoice_total - payment_total - credit_total > 0

A. updates the credit_total column for the first invoice with 10 in the vendor_id column and a balance so it doesn't have a balance due.
B. updates the credit_total column for all invoices with 10 in the vendor_id column and a balance due so they don't have a balance due.
C. updates the credit_total column for all invoices with a balance due so they don't have a balance due.

Answer 1

The UPDATE statement modifies the credit_total field for all invoices associated with vendor_id 10 that have a remaining balance due. It sets credit_total to the difference between invoice_total and payment_total.

Step-by-step explanation:

The UPDATE statement in question specifically targets records in the invoices table where the vendor_id is equal to 10 and where there is a balance due. The balance due is calculated by the expression invoice_total - payment_total - credit_total > 0. Therefore, this statement:

B. updates the credit_total column for all invoices with 10 in the vendor_id column and a balance due so they don't have a balance due. The updated credit_total will be set to the difference between invoice_total and payment_total, effectively clearing the balance.

The UPDATE statement described in the question updates the credit_total column in the invoices table. It subtracts the payment_total from the invoice_total and assigns the result to credit_total. This update only applies to invoices with a vendor_id of 10 and where the calculated credit_total is greater than 0.