How Can I Convert SQL CASE Statements to LINQ?

LINQ CASE Statements: A Deeper Dive

In LINQ (Language Integrated Query), CASE statements provide a convenient way to evaluate multiple conditions and return different values based on those conditions. To convert the provided CASE statement to LINQ, one can leverage ternary conditional operators or lambda expressions to achieve similar functionality.

Consider the following example:

// Original CASE statement
osc_products.products_quantity =
CASE 
    WHEN itempromoflag <> 'N' THEN 100000
    WHEN itemcat1 IN ('1','2','31') AND itemsalestatus = 'S' THEN 100000
    WHEN itemsalestatus = 'O' THEN 0
    ELSE cds_oeinvitem.itemqtyonhand - cds_oeinvitem.itemqtycommitted 
END  

To translate this to LINQ, we can employ ternary conditional operators:

var newQuantity = (itempromoflag != 'N') ? 100000 :
    ((itemcat1 == '1' || itemcat1 == '2' || itemcat1 == '31') && itemsalestatus == 'S') ? 100000 :
    (itemsalestatus == 'O') ? 0 :
    cds_oeinvitem.itemqtyonhand - cds_oeinvitem.itemqtycommitted;

Alternately, lambda expressions can be used for a more concise representation:

var newQuantity = (itempromoflag != 'N') ? 100000 :
    ((itemcat1 == '1' || itemcat1 == '2' || itemcat1 == '31') && itemsalestatus == 'S') ? 100000 :
    (itemsalestatus == 'O') ? 0 :
    () => cds_oeinvitem.itemqtyonhand - cds_oeinvitem.itemqtycommitted;

In these examples, the ternary operator and lambda expressions perform similar conditional checks and return the appropriate value based on the condition being met.

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