what is the use of into and let in LINQ. please help

Hi siddarth,

 

Into : The Into keyword allows creating a temporary variable to store the results of a group, join, or select clause into a new variable.

var em = from e in emp

group e by new{ e.DeptId}                           
into gEmp                            
where gEmp.Count() > 1                        
select new { gEmp.Key.DeptId, salary = gEmp.Sum(t => t.Salary) };

In the above query, after applying into on grouping, it creates a IGrouping type gEmp variable, which is used to apply the next filter.

Note: Into is used when you want to perform an operation on grouped data.

Let : The Let keyword allows storing the results of a query which can be used in a subsequent query; i.e., it creates a new variable and initializes it with the result of the expression you supply.

var em = from e in emp                      
group e by new { e.Salary, e.Id }                          
into gEmp                          
let avgsal = (gEmp.Sum(t => t.Salary) / gEmp.Count())                          
where gEmp.Key.Salary == avgsal                          
select new { gEmp.Key.Salary, gEmp.Key.Id };

 

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