June 2011 – Dhananjay Kumar

Video Executing SQL Query in LINQ to SQL


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ExecutingSQLQuery
{
    class Program
    {
        static void Main(string[] args)
        {
            DataClasses1DataContext context = new DataClasses1DataContext();
            int a = 1;
            var result = context.ExecuteQuery<Person>("select * from Person where PersonID= {0}",a);
            foreach (var r in result)
            {
                Console.WriteLine(r.FirstName + r.LastName);
            }
            Console.ReadKey(true);
            var result1 = context.ExecuteQuery<Person>("select * from Person");
            foreach (var r in result1)
            {
                Console.WriteLine(r.FirstName + r.LastName);
            }

            Console.ReadKey(true);
        }
    }
}

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Learning Video Executing Stored Procedure in LINQ to SQL

Source code used in Video


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace StoredProcedure
{
    class Program
    {
        static void Main(string[] args)
        {
            DataClasses1DataContext context = new DataClasses1DataContext();
            // Call SP with parameter
            int studentID = 2;
            var result=  context.GetStudentGrades(studentID);
            foreach (var r in result)
            {
                Console.WriteLine(r.Grade);
            }

            // call SP with parameter
            int? a=1;
            var result1 = context.GetStudentCount(ref a);
            Console.WriteLine(a);

            Console.ReadKey(true);

        }
    }
}

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Windows Phone SDK 7.1 Beta 2 released: installation steps

Note : Content of this post is taken as it is from release note of Windows Phone SDK 7.1 . Please read release document more carefully. I have listed the breaking relase opints as it is from there. Original content is on relase note.

On 27^th June 2011 Windows Phone SDK 7.1 Beta 2 got released.

You can download it from below link,

http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=26648

Release information is as below,

If you installed Windows Phone Developer Tools 7.1 Beta 1, you must uninstall it before installing Windows Phone SDK 7.1 Beta 2.

Few points ,

There are many known issue in the release. So before installing read release document very carefully.
There are many breaking changes like

Touch input for the ScrollViewer and ListBox controls happens on an independent thread by default, instead of on the UI thread.
Image decoding happens on a background thread by default, instead of on the UI thread.
The TaiwanCalendar class has been removed from the API.
The OnCancel override method was removed from the ScheduledTaskAgent class.
The IsRunningSlowly property was removed from the GameTimerEventArgs class.
IExecuteResult was removed from the Windows Phone OS 7.1 API.
The MotionReading property types have changed.
The Background Transfer Service folder in isolated storage was renamed.
Tile data in isolated storage must use the folder Shared\ShellContent.
The ShellTileEnumerator class was removed.
Background agents are not launched in the debugger by using the Add and Find methods.
The maximum and default database and buffer pool size values are now lower for SQLCE databases.
. Connection string parameters that are not supported are removed.
. Microsoft.Devices.YCrCbPixelLayout was renamed to Microsoft.Devices.YCbCrPixelLayout.
Microsoft.Devices.CaptureResolution was removed.

Installation of Winows Phone SDK 7.1 Beta 2

First uninstall Windows Phone SDK 7.1. Uninstall below items

Windows Phone SDK 7.1 Beta
Windows Phone Emulator (Beta)
Microsoft Windows Phone Developer Tools 7.1

After uninstalling Beta 1 install Beta 2.

Screen shorts are as below Smile

Enjoy with Windows Phone 7.1 Beta 2 Smile


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----------------------------------------------------------

Executing SQL Query using LINQ to SQL

In this post, I will discuss how we can execute a SQL Query directly from LINQ.

Explanation

To execute SQL query there is a method in DataContext class called ExecuteQuery

ExecuteQuery takes two input parameter

1. SQL Query as string

2. Parameters used in SQL query

And it returns an IEnumerable.

Example

Below code will execute a simple select statement and it will return IEnumerable<Person>

If you want to pass some parameter in the query, you can pass that as second parameter.

If you want pass input parameter as hardcoded value you can very much do that as below

For your reference source code is as below,


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Data.Linq;

namespace Relatedtable
{
    class Program
    {

        static DataClasses1DataContext context;
        static void Main(string[] args)
        {
            context = new DataClasses1DataContext();

            var result = context.ExecuteQuery<Person>("select * from Person");
            foreach (var r in result)
            {
                Console.WriteLine(r.PersonID + r.FirstName);
            }

            int idToPass = 1;
            var result1 = context.ExecuteQuery<Person>
                          ("select * from Person where PersonID={0}", idToPass);
            foreach (var r in result1)
            {
                Console.WriteLine(r.PersonID + r.FirstName);
            }

            Console.ReadKey(true);

            var result2 = context.ExecuteQuery<Person>
                          ("select * from Person where PersonID='1'");
            foreach (var r in result2)
            {
                Console.WriteLine(r.PersonID + r.FirstName);
            }

            Console.ReadKey(true);
}
}
}

On pressing F5 you should get output as below,

I hope this post was useful. Thanks for reading Smile

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Fetching different values in LINQ Concurrency conflict

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If you have not read my post Resolving Concurrency conflicts in LINQ then I strongly recommend you to read that. This post is a simple added extension of said post.

After reading resolving concurrency conflict in LINQ you are pretty much aware of resolving mechanism of concurrency conflicts. Now assume a requirement that you need to print or fetch

Current value of object
Original value of object on context
Current data base value.

This is very much possible by

Enumerating over MemberConflicts of ChangeConflict object.
Fetching MemberChangeConflict in object of MemberConflict

In child Foreach loop you can fetch values as ,

Catch statement should be modified as below to fetch and print different values.

For reference you can find full source code below,


using System;
using System.Linq;
using System.Data.Linq;

namespace Concurrency
{
    class Program
    {
        static void Main(string[] args)
        {

            DataClasses1DataContext context = new DataClasses1DataContext();

            #region without handling Conflict
            //Person personToUpdate = (from r in context.Persons
            //                         where r.PersonID == 1
            //                         select r).FirstOrDefault();
            //personToUpdate.FirstName = "John Papa";
            //context.SubmitChanges();

            #endregion

            #region hanlding conflict

            try
            {
                Person personToUpdateConflict = (from r in context.Persons
                                                 where r.PersonID == 1
                                                 select r).FirstOrDefault();
                personToUpdateConflict.FirstName = "John";
                context.SubmitChanges(ConflictMode.FailOnFirstConflict);

            }
            catch (ChangeConflictException c)
            {
                foreach (ObjectChangeConflict o in context.ChangeConflicts)
                {
                    o.Resolve(RefreshMode.KeepChanges);

                    foreach (MemberChangeConflict c1 in o.MemberConflicts)
                    {
                        var currentValue = c1.CurrentValue;
                        var originalValue = c1.OriginalValue;
                        var dataBaseValue = c1.DatabaseValue;

                        Console.WriteLine("Current Value of Object " + c1.CurrentValue);
                        Console.WriteLine("Original value in context " + c1.OriginalValue);
                        Console.WriteLine("Database value " + c1.DatabaseValue);
                    }

                }
                context.SubmitChanges();

            }

            #endregion
            Console.ReadKey(true);
        }
    }
}

On running application, you should get output as below.

I hope this post was useful. Thanks for reading Smile

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