LINQ QUERY

Ankit Shukla

11y1.3kLINQ

Hello,

I am new in LINQ. There is a query given below. I want to know that what is the meaning of 'into g' in 2nd line and 'g.key' in 4th line.

//To achieve Select CategoryId, Count(CategoryID) As FieldName From ProductMst Group By CategoryId you need

to write follofing linq Query

var Result14 = from p in db.ProductMst

group p by p.CategoryID into g

select new {

CategoryId = g.Key,

FieldName = g.Count()

};

5 Replies

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Shuvojit Halder11y ago
Accepted answer
into g means , your group by query result will store in g. and g.key means ,you have grouped by one id field, so, g.key is the id field of the query.

and if you need more result then you can use

yourfield1=g.select(a=>a.yourfield)
Nilesh Jadav11y ago
May be this link work for you :

http://visualcsharptutorials.com/linq/group-by-clause

http://blogs.msdn.com/b/mitsu/archive/2007/12/22/playing-with-linq-grouping-groupbymany.aspx
Rajeev Punhani11y ago
The Into keyword allows creating a temporary variable to store the results of a group, join or select clause into a new variable.See this article it explains http://www.c-sharpcorner.com/UploadFile/97fc7a/let-vs-into-keywords-in-linq/
Upendra Pratap Shahi11y ago
Hello,

Into

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

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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.

Key-

· The key consists of three parts, implemented by a Tuple[^] class.

· The three items of the key represent the three sort criteria: position, capital letter, element string as lower case.

· To achieve the 1^st criterion, strings with only lower letters have the "capital letter position" set toint.MaxValue, leading to the correct sort constraint for these cases.

· The IComparer implementation of the Compare method is straight forward with this key: compare the 1^st criterion, if equal go to the 2^nd, if that is still equal, take the last one.
Manoj Bhoir11y ago
Hi,

When used with the select keyword, into will end the scope.
When used with the join keyword, into will add a variable containing all of the matching items from the join. (This is called a Group Join)

And With the new keyword they are building an anonymous object with only those two fields from g with fields key and count.

So here first in your query you are selecting result into g variable with all fields present in p / db.ProductMst. and after that from all these fields you are selecting only two fields using Select New from g.