Regarding FirstOrDefault or SingleOrDefault

Question

User88744855 posted

what kind of data FirstOrDefault or SingleOrDefault will return.

suppose my query return 3 record like

empid  ename  salary
-----  -----  ------
1      joy    1500
2      rob    4500
3      jen    6500

so if we use FirstOrDefault or SingleOrDefault then what kind of resultset i will get. please explain with example. thanks

Answer 1

User377791177 posted

http://stackoverflow.com/questions/1745691/linq-when-to-use-singleordefault-vs-firstordefault-with-filtering-criteria

Answer 2

User3866881 posted

Hello：）

FirstOrDefault should be used to a collection that implemented IQueryable<T> interface. So a common array, if you want to use it, you should convert it to Query and use it, look at this sample——http://msdn.microsoft.com/zh-cn/library/bb301896(VS.95).aspx

 int[] numbers = { };
         // Get the first item in the array, or else the
         // default value for type int (0).
         int first = numbers.AsQueryable().FirstOrDefault();

Compared with this, SingleOrDefault can be used on any collection that has implemented the interface of IEnumerable<T>.