--  SWITCH evaluates its first argument (value) and then uses the next
--  remaining parameters in pair: the first element is used to match the value
--  the second as the result if there is a match.
--  The last argument, alone, provides the no-match value and it defaults 
--  to blank.
DEFINE MEASURE Sales[Discounted Sales] = 
    SUMX ( 
        VALUES ( 'Product'[Category] ),
        VAR DiscountPct = 
            SWITCH ( 
                'Product'[Category],
                "Audio", 0.15,
                "Computers", 0.2,
                "Cell phones", 0.13,
                0
            ) 
        RETURN
            [Sales Amount] * (1 - DiscountPct )
    )
EVALUATE
SUMMARIZECOLUMNS ( 
    'Product'[Category],
    "Sales Amount", [Sales Amount],
    "Discounted sales", [Discounted Sales]
)
ORDER BY [Category]

--  A common usage of SWITCH is to use a constant as the value argument
--  and expressions in the pairs. This technique allows more flexibility
--  even though it somewhat lacks in readability.
DEFINE MEASURE Sales[Discounted Sales] = 
    SUMX ( 
        SUMMARIZE ( Sales, Sales[Net Price], Product[Category] ),
        VAR DiscountPct = 
            SWITCH ( 
                TRUE,
                Sales[Net Price] <= 150, 0.15,
                Sales[Net Price] <= 1000, 0.2,
                Product[Category] = "Audio", 0.13,
                0
            ) 
        RETURN
            [Sales Amount] * (1 - DiscountPct )
    )
EVALUATE
SUMMARIZECOLUMNS ( 
    'Product'[Category],
    "Sales Amount", [Sales Amount],
    "Discounted sales", [Discounted Sales]
)
ORDER BY [Category]

--  Using SWITCH the first condition met defines the result.
--  In the following example, the second condition (<= 150) will never be
--  met, because the first one is less restrictive.
DEFINE MEASURE Sales[Discounted Sales] = 
    SUMX ( 
        SUMMARIZE ( Sales, Sales[Net Price], Product[Category] ),
        VAR DiscountPct = 
            SWITCH ( 
                TRUE,
                Sales[Net Price] <= 1000, 0.2,
                Sales[Net Price] <= 150, 0.15,
                Product[Category] = "Audio", 0.13,
                0
            ) 
        RETURN
            [Sales Amount] * (1 - DiscountPct )
    )
EVALUATE
SUMMARIZECOLUMNS ( 
    'Product'[Category],
    "Sales Amount", [Sales Amount],
    "Discounted sales", [Discounted Sales]
)
ORDER BY [Category]