LINQ to Entities Small code to test data retrieval C# WinForms

Samio

14y2.8kLINQ

Hi

Could not get this to work, When I Run project no console is displayed

also as I am new to Entity Framework with C# winforms, I would like to ask how to fill a TextBox with a context item.

I am using Visual studio 2010 version and MS SQL 2008 Express.

Thank you

Code:

using System;
using System.Data.Objects;
using System.Linq;
using System.Windows.Forms;

namespace MyNameSpace
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void BtnOk_Click(object sender, EventArgs e)
{

using (LINQtoEntitiesEntities MyEntities = new LINQtoEntitiesEntities())
{
ObjectQuery Employee = MyEntities.Employee;
var query = from p in Employee
where p.FirstName == "Jane"
select new { p.ID, p.LastName, p.FirstName, p.Birth };
foreach (var ligne in query)
Console.WriteLine(ligne.ID + " " + ligne.LastName + " " + ligne.FirstName);
}
Console.Read();
}
}
}

13 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
Like Jignesh, I can't see anything wrong with the code.

Possibly, the name in the table uses different capitalization or has some leading or trailing spaces. To test for this, I'd try replacing:

where p.Nom == "JANE"

with:

where p.Nom.Trim().ToUpper() == "JANE"

To put the result in a TextBox, you'll first need to set its Multiline property to true. The code will then be :

string text = "";

foreach (var ligne in query)
{
text += ligne.ID + " " + ligne.LastName + " " + ligne.FirstName + "\r\n";
}

textBox1.Text = text;
Samio14y ago
Please see my new Topic here
thank you
Jignesh Trivedi14y ago
Hi,

It would grate if you create new topic.
thanks
Samio14y ago
As I am new here, and as I have other questions related to the same code,

May I use the same Topic or it should be better that I create a new topic ?
Vulpes14y ago
Sorry, the last line should be within the using statement:

using (LINQtoEntitiesEntities MyEntities = new LINQtoEntitiesEntities())
{
ObjectQuery Employee = MyEntities.Employee;
var query = (from p in Employee
where p.FirstName == textBox1.Text.Trim()
select p.Birth).FirstOrDefault();
if (query != null) label1.Text = query.ToString();
}
Jignesh Trivedi14y ago
Hi
Try

using (LINQtoEntitiesEntities MyEntities = new LINQtoEntitiesEntities())
{
    ObjectQuery Employee = MyEntities.Employee;
    var query = (from p in Employee
    where p.FirstName == textBox1.Text.Trim()
    select p.Birth).FirstOrDefault();
if (query != null) label1.Text = query.ToString();
}
hope this help.
Samio14y ago
@Jignesh,

Sorry, it was my mistake, as the code was written using French words, and I omitted to translate that one.

Thank you anyway.
Samio14y ago
@Vulpes,

I used your code and obtained "The name 'query' does not exist in the current context"

What have I to do ?
Vulpes14y ago
The query for that would be:

using (LINQtoEntitiesEntities MyEntities = new LINQtoEntitiesEntities())
{
ObjectQuery Employee = MyEntities.Employee;
var query = (from p in Employee
where p.FirstName == textBox1.Text.Trim()
select p.Birth).FirstOrDefault();
}

if (query != null) label1.Text = query.ToString();
Jignesh Trivedi14y ago
hi,

nom is Name (full name) am I right?is it combination of Last name and first name?
If yes then I think keyword "contain" will help you.

Like:
var query = from p in MyEntities.Employee
where p.Nom.Contains("JANE")
select new { p.ID, p.LastName, p.FirstName, p.Birth };

After this Check Result in Query.

hope this help.
Samio14y ago
Vulpes and Jignesh

Both of you are right, Finaly I could run it,

Please I would ask how to use the same code when looking for a single record. i.e. searching for TextBox1 content (Name) to retrieve Label1.Text (BirthDate).

Many Thanks
Samio14y ago
Hi Jignesh,

The record "JANE" is in the table, something else is making Console not work.

I add that I use Visual Studio 2010 with SP1.

And would like to use the same code to fill a TextBox in Form1, in stead of to use Console, to ensure from where the issue is coming.

Please could you make the code modification ?
Jignesh Trivedi14y ago
hi,
Code is correct to retrieve data, but it may possible your filter is not correct means "JANE " data is not in database please check it.

using (LINQtoEntitiesEntities MyEntities = new LINQtoEntitiesEntities())
{
    var query = from p in MyEntities.Employee
                where p.Nom == "JANE"
                select new { p.DepartmentId, p.EmployeeCode };
    foreach (var ligne in query)
    {
        Console.WriteLine(ligne.ID + " " + ligne.LastName + " " + ligne.FirstName);
    }
}
hope this help.