I under stand the s is an alias for DWDAYSALESFACT but why was the s chosen for SALES over d for DAY in DWDAYSALESFACT

Step 3 of 5 A Consider the following query to display the TOTSALES by customer, month and product, with subtotals by customer and by month and a grand total for all the product sales. The SOL command is written using SQL-Server 2014 syntax. Query: SELECT s.CUS CODE, t.TM MONTH, s.P CODE, SUM(S.SALE UNITS s.SALE PRICE) AS TOTSALES FROM DWDAYSALESFACT as s INNER JOIN DWTIME as t on s.TM.ID=t.TM.ID GROUP BY ROLLUP (s.CUS_CODE, t.TM MONTH, s.P CODE) ORDER BY s.CUS CODE, t.TM MONTH, S.P CODE Step 3 of 5 A Consider the following query to display the TOTSALES by customer, month and product, with subtotals by customer and by month and a grand total for all the product sales. The SOL command is written using SQL-Server 2014 syntax. Query: SELECT s.CUS CODE, t.TM MONTH, s.P CODE, SUM(S.SALE UNITS s.SALE PRICE) AS TOTSALES FROM DWDAYSALESFACT as s INNER JOIN DWTIME as t on s.TM.ID=t.TM.ID GROUP BY ROLLUP (s.CUS_CODE, t.TM MONTH, s.P CODE) ORDER BY s.CUS CODE, t.TM MONTH, S.P CODE