The tblMagInfo table contains three fields. The Code and Cost fields are numeric

Question

The tblMagInfo table contains three fields. The Code and Cost fields are numeric. The Magazine field contains text. The dataset's name is MagsDataSet.

Write a LINQ statement that arranges the records in descending order by the Cost field.

Write a LINQ statement that selects records having a code of 9.

Write a LINQ statement that selects records having a cost of $3 or more.

Write a LINQ statement that selects the Daily Food Guide magazine.

Write a LINQ statement that selects magazines whose name begins with the letter G (in either uppercase or lowercase).

Write a LINQ statement that calculates the average cost of a magazine.

Explanation / Answer

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;

public partial class LINQuery : System.Web.UI.Page
{
DataTable tblMagInfo=new DataTable();
DataTable tblResult = new DataTable();
DataColumn dc;
DataRow dr;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
dc = new DataColumn("Code");
tblMagInfo.Columns.Add(dc);
dc = new DataColumn("Cost", typeof(int));
tblMagInfo.Columns.Add(dc);
dc = new DataColumn("Magazine");
tblMagInfo.Columns.Add(dc);

dr = tblMagInfo.NewRow();
dr["Code"] = 1;
dr["Cost"] = 3;
dr["Magazine"] = "Daily Food Guide";
tblMagInfo.Rows.Add(dr);
dr = tblMagInfo.NewRow();
dr["Code"] = 2;
dr["Cost"] = 1;
dr["Magazine"] = "Digital World";
tblMagInfo.Rows.Add(dr);
dr = tblMagInfo.NewRow();
dr["Code"] = 4;
dr["Cost"] = 4;
dr["Magazine"] = "Genuis Magazine";
tblMagInfo.Rows.Add(dr);
dr = tblMagInfo.NewRow();
dr["Code"] = 6;
dr["Cost"] = 5;
dr["Magazine"] = "George Ideas";
tblMagInfo.Rows.Add(dr);
dr = tblMagInfo.NewRow();
dr["Code"] = 7;
dr["Cost"] = 2;
dr["Magazine"] = "Computer World";
tblMagInfo.Rows.Add(dr);
dr = tblMagInfo.NewRow();
dr["Code"] = 9;
dr["Cost"] = 1;
dr["Magazine"] = "Daily Motion";
tblMagInfo.Rows.Add(dr);

//1. LINQ statement that arranges the records in descending order by the Cost field
var Rows = (from row in tblMagInfo.AsEnumerable()
orderby row["Cost"] descending
select row);
tblResult = Rows.AsDataView().ToTable();
tblResult.Rows.Clear();

//2. LINQ statement that selects records having a code of 9
var Rows1 = (from row in tblMagInfo.AsEnumerable()
where row.Field<string>("Code").ToString().Contains("9")
select row);//.Count();

tblResult = Rows1.AsDataView().ToTable();
tblResult.Rows.Clear();

//3. LINQ statement that selects records having a cost of $3 or more
var Rows2 = tblMagInfo.AsEnumerable()
.Where(x => x["Cost"] != DBNull.Value)
.Count(x => x.Field<int>("Cost") > 3);

//4. LINQ statement that selects the Daily Food Guide magazine.
var Rows3 = (from row in tblMagInfo.AsEnumerable()
where row.Field<string>("Magazine").Equals("Daily Food Guide")
select row);

tblResult = Rows3.AsDataView().ToTable();
tblResult.Rows.Clear();

// 5. LINQ statement that selects magazines whose name begins with the letter G (in either uppercase or lowercase)
var Rows4 = (from row in tblMagInfo.AsEnumerable()
where row.Field<string>("Magazine").ToString().Contains("G")
select row);
tblResult = Rows3.AsDataView().ToTable();
tblResult.Rows.Clear();

//6. LINQ statement that calculates the average cost of a magazine.
var Rows5 = tblMagInfo.AsEnumerable()
.Where(x => x["Cost"]!= DBNull.Value)
.Average(x => x.Field<int>("Cost"));

}
}
}

//Note: i created a datatable named it as tblMagInfo , fill data with temporary data ,

written linq to get your records back as data table.

If any issues please reply to me.

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