比較實體SQL中的日期

Question

比較日期的正確eSQL語法是什麼？

等效LINQ到實體表達會是這個樣子：

var lastYearsShipments = from p in MyDataServiceContext.Products 
         where p.ShipDate.Value.Year == DateTime.Now.Year - 1 
         select p; 

Answer 1

他們說這是acceptable to answer your own question，所以這裏去...

var predicate = string.Format(
    "Year(it.ShipDate) == Year(cast('{0}' as System.DateTime)) -1", 
    System.DateTime.Now); 

var lastYearsShipments = 
    myQuery.Products.Where(predicate); // myQuery is type ObjectQuery<T> 

參見：msdn documentation

Answer 2

string datetimeFormatter = "yyyy-MM-dd HH:mm"; 

var predicate = string.Format("Year(it.ShipDate) == Year(DATETIME'{0}')) -1", System.DateTime.Now.ToString(datetimeFormatter)); 

var lastYearsShipments = myQuery.Products.Where(predicate);