What precisely are aggregates?

I am having some trouble with this for an assignment in Database. I am trying to create some queries for this homework: Assignment 5: Data Definition language and Transaction in MySQL This is what I am currently working on: On June 3, 2019, customer ‘10010’ makes a payment of $100 in cash. The payment ID is 3428. The query as it is as of this moment: SELECT PAYMENTINSERT INTO PAYMENT (PMT_ID,PMT_DATE,CUS_CODE,PMT_AMT,PMT_TYPE,PMT_DETAILS)VALUES(3428,6-3-2019,10010,100.00,cash,account),UPDATE CUSTOMERSET CUS_BALANCE = CUS_BALANCE + 100WHERE CUS_CODE=10010,COMMIT 2. On May 11, 2019, customer ‘10012’ makes a credit purchase of one unit of product ‘11QER/31’ with a unit price of $110.00; the invoice total is $118.80. The invoice number is 10983, and this invoice has only one product line. [note: no payment has been made here] The Query as of now: BEGIN TRANSACTION; INSERT INTO VOICE VALUES (10983, 10012, ’5-11-2019’), INSERT INTO LINE VALUES (10983, 1, ‘11QER/31’, 1, 110.00), UPDATE…

How is a clustered index made, and what are the main differences between a clustered index and a sparse index?

What are the key differences between a clustered index and a sparse index?