Starts with question

[Anonymous]

I have a measure Total Sales = sum(SALES[Sales])

If the customer name starts with "Acme" reduce SALES[Sales] by 12%, if the customer name starts with "Vect", reduce SALES[Sales] by 10%, if customer name starts with "Merc", reduce SALES[Sales] by 9%, else sum(SALES[Sales]).

1. Would it be more efficient to add a column on the SALES table called [Adjusted Sales] that figures this calculation, then create a new measure Total Adjusted Sales = sum(SALES[Adjusted Sales]),  or just do this calculation with a measure?  

2. Whichever one is more efficient, how would I write it?  The column would be in M language and the measure would be in DAX and I'm not sure how to write this formula in either.

Thanks for your help.

[parry2k · Accepted solution]

@Anonymous I would recommend to create a column with adjusted sales and then use this new column in the measures

Adjusted Sales Column = 
VAR __start = LEFT ( Table[Customer], 4 )
RETURN
SWITCH ( __start,
 "ACME", .88,
 "VECT", .90,
 "MERC", .81,
1
) 
*
Table[Sales]

[amitchandak]

@Anonymous ,

Try like

sumx(SALES,
Switch( True(),
left((SALES[customer]),4) = "Acme" , SALES[Sales] *.88,
left((SALES[customer]),4) = "Vect" , SALES[Sales] *.90,
left((SALES[customer]),4) = "Merc" , SALES[Sales] *.9,
SALES[Sales])
)