Who order from the west region on August 12, 2013, and received a discount of 0.2?
Who refers to "Customer Name"; on August 12, 2013 refers to "Order Date" = '2013-08-12'; discount of 0.2 refers to discount = 0.2
SELECT DISTINCT T2.`Customer Name` FROM west_superstore AS T1 INNER JOIN people AS T2 ON T1.`Customer ID` = T2.`Customer ID` WHERE T1.`Order Date` = '2013-08-12' AND T1.Discount = 0.2 AND T1.Region = 'West'