Standard operators and methods used by LINQ

# Region LINQ standard query operator (LAMBDA Method) Note: C # overload with Integer Parameters (indexes) in standard query operators is not supported

// 1. Filter Method for standard query operators -- where
// Iqueryable <student> stu1 = dB. Student. Where (S => S. ssex = "male ");
// Gridview1.datasource = stu1;
// Gridview1.databind ();


// 2. Select of the standard query operator

// Var stu2 = dB. Student. Select (S => New {S. Sno, S. sname, S. Sage}); // This is called an anonymous object
// Gridview2.datasource = stu2;
// Gridview2.databind ();


// 3. sorting method of standard query operators -- order
// Sort in ascending order
VaR stu3 = dB. Student. orderby (S => S. Sage );
Gridview1.datasource = stu3;
Gridview1.databind ();

// Sort by multiple criteria in descending order
VaR stu4 = dB. Student. orderbydescending (S => S. Sage). thenbydescending (S => S. SnO );
Gridview2.datasource = stu4;
Gridview2.databind ();


// 4. Join set of standard operators -- join
VaR stu5 = dB. student. join (dB. stucourse, S => S. sno, Stu => Stu. sno, (S, Stu) => New {SnO = S. sno, scsno = Stu. sno, S. sname, Stu. CID });
Gridview2.datasource = stu5;
Gridview2.databind ();

// Left join
VaR leftjoin = from Stu in db. Student
Join SC in db. stucourse
On Stu. Sno equals SC. SnO
Into temp
From t in temp. defaultifempty ()
Select New {Stu. Sno, Stu. Sage, cid = T = NULL? 0: T. CID };

// Right join
VaR right = from SC in db. stucourse
Join Stu in db. Student
On SC. Sno equals Stu. SnO
Into temp
From TT in temp. defaultifempty ()
Select New {SC. CID, SC. Sno, sname = TT = NULL? "": TT. sname };

// 5. Group of standard operators-groupby
// Group by age
VaR stu6 = dB. Student. groupby <student, int> (S => (INT) S. Sage );
List <igrouping <int, student> list2 = stu6.tolist ();
Foreach (igrouping <int, student> item in list2)
{
// Grouping conditions of the output Group
Response. Write (string. Format ("group: {0} <br/>", item. Key ));
// Traverse all elements in the group
Foreach (student ST in item)
{
Response. Write (string. Format ("Name: {0}", st. sname ));
}
Response. Write ("<br/> ");
}

// 6. Paging data of standard operators-Skip + take
// Assume that each page has 5 Records
// Int pagesize = 2;
// Return list. Skip (pageindex-1) * pagesize). Take (pagesize). tolist ();
VaR pageone = dB. Student. Skip <student> (24). Take (6 );
Gridview1.datasource = pageone;
Gridview1.databind ();

# Endregion

 

 

Additional:

Int [] numbers = {0, 30, 15, 90, 85, 40, 75, 20 ,};
Int [] arr = {};
Int first = numbers. First <int> (M => m> 35); // return the first record 90 that meets the conditions.
Int last = numbers. Last <int> (n => n <40); // returns the last record 20 that meets the conditions.
Bool allresult = numbers. All <int> (Mm => mm <100); // determines whether all elements meet true.
Bool allresult2 = numbers. All <int> (Mm => MM> 5); // false
Bool anyresult = numbers. Any (); // return true if there is an element in numbers
Bool anyresult1 = arr. Any (); // returns false if no element in arr
Bool anyresult2 = numbers. Any <int> (Mm => mm <1); // returns true if one element meets the conditions.
Bool anyresult3 = numbers. Any <int> (Mm => MM> 89); // true
Bool anyresult5 = numbers. Any (M => m> 200); // false

Standard operators and methods used by LINQ