Linq queries for beginners


Following are some of the basic Linq command/samples for those who just want to start learning Linq. So this will help a lot to all the beginners to easily understand Linq queries.

// Basic Query
// To achieve  Select * From ProductMst  you need to write follofing linq Query
  var Result1 = from p in db.ProductMst
                 select p;
// To achieve  Select ProductID, ProductName, Price From ProductMst you need to write follofing linq Query
    var Result2 = from p in db.ProductMst
                 select new {
                     p.ProductID,
                     p.ProductName,
                     p.Price
                 };

// Where Clause Query
// To achieve  Select * From ProductMst Where ProductID = 1 you need to write follofing linq Query
    var Result3 = from p in db.ProductMst
                 where p.ProductID == 1
                 select p;

// To achieve Select * From ProductMst Where SupplierId =2 and Price > 10 you need to write follofing linq Query
    var Result4 = from p in db.ProductMst
                 where p.SupplierID == 2 && p.Price > 10
                 select p;


// To achieve Select * From ProductMst Where SupplierId =2 Or SupplierId=5 you need to write follofing linq Query
    var Result5 = from p in db.ProductMst
                 where p.SupplierID == 2 || p.SupplierID == 5
                 select p;

// Order By Query
//To achieve   Select * From ProductMst Order By ProductId you need to write follofing linq Query
    var Result6 = from p in db.ProductMst
                 orderby p.ProductID
                 select p;

// To achieve  Select * From ProductMst Order By ProductId Desc you need to write follofing linq Query
    var Result7 = from p in db.ProductMst
                 orderby p.ProductID descending
                 select p;

// To achieve  Select * From ProductMst Order By CategoryId, Price Desc you need to write follofing linq Query
    var Result8 = from p in db.ProductMst
                 orderby p.CategoryID, p.Price descending
                 select p;

// Top Query
//To achieve Select Top 5 * From ProductMst you need to write follofing linq Query
    var Result9 = (from p in db.ProductMst
                 select p).Take(5);

//To achieve Select Top 1 * From ProductMst you need to write follofing linq Query
    var Result10 = (from p in db.ProductMst
                   select p).Take(1);
     or

    var Result11 = (from p in db.ProductMst
                   select p).First();

// Distinct Query
//To achieve Select Distinct CategoryId From ProductMst you need to write follofing linq Query

    var Result13 = (from p in db.ProductMst
                   select p.CategoryID).Distinct();

// Group By Query
//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()
                  };

//To achieve Select CategoryId, Avg(UnitPrice) As NewField From ProductMst Group By CategoryId you need to write follofing linq Query
    var Result15 = from p in db.ProductMst
                  group p by p.CategoryID into g
                  select new {
                      CategoryId = g.Key,
                      FieldName = g.Average(S => S.Price)
                  };

// Union Query
//To achieve Select * From ProductMst Where CategoryId =1 union Select *  From ProductMst Where CategoryId = 2 you need to write follofing linq Query
    var Result17 = (from p in db.ProductMst
                   where p.CategoryID == 1
                   select p).Union(
                       from m in db.ProductMst
                       where m.CategoryID == 2
                       select m
                   );