How can I update table in Entity framework?

Question

I am calling a web service from my MVC project and if it is successful then it returns process complete. This result, I am storing in variable called y.

var y = Here pass required parameters and if it is successfull store result in y

when I put breakpoint here and if process complete, I can see result in var y.

So if process complete I need to update my table. For this can I do like this ?

  if( y = "Process complete")
  {
     update table code here 
  }

and I don't know how to update table in Entity Framework. Here I need to update table called table1 and set column2 = 1, column 3 = value of column 4 where column 1 = value of column 1.

What I know for this is :

UPDATE tableName 
SET column2 = 1, column3 = context.FirstOrDefault().column4  
WHERE column1 =  context.FirstOrDefault(). column1

Update :

Hi i got to know how to write code to update table.But when i put break-point and come to savechanges method i am getting Property export is part of the objects key information and cannot be modified error.

This is the code i am using to update my table :

      var rec = (from s in geton.table_1
      where s.on_id == geton.table_1.FirstOrDefault().on_id
      select s).FirstOrDefault();
      rec.export = 1;
      rec.on_date = geton.table_1.FirstOrDefault().on_date;
      geton.SaveChanges();

First your update query is incorrect, correct is UPDATE tablename... Second have you read any EF tutorials?codeproject.com/Articles/363040/… — Lev
– Lev, Commented Sep 26, 2013 at 9:53

Jatin patil · Accepted Answer · 2013-09-26 10:03:04Z

3

A new entity can be added to the context by calling the Add method on DbSet. This puts the entity into the Added state, meaning that it will be inserted into the database the next time that SaveChanges is called.

For example:

using (var context = new YourContext())
{
    var record = new TypeName { PropertyName = "Value" };
    context.EntityName.Add(record );
    context.SaveChanges();
}

For More Info :

http://msdn.microsoft.com/en-us/library/bb336792.aspx

http://msdn.microsoft.com/en-us/data/jj592676.aspx

http://www.entityframeworktutorial.net/significance-of-savechanges.aspx

answered Sep 26, 2013 at 10:03

Jatin patil

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2 Comments

Raj Over a year ago

hi thanks for reply. where can i add my where condition if i follow your approach? I wrote code like this inside my entity : var record = new type { export = 1 }; context.myentity.add(record); context.savechanges();. Here how can i add where condition which should check for x.ID == ID

Jatin patil Over a year ago

Means You want to save changes if your condition gets satisfied?

Thewads · Accepted Answer · 2013-09-26 17:31:18Z

0

Hi i got to know how to write code to update table.But when i put break-point and come to savechanges method i am getting Property export is part of the objects key information and cannot be modified error.

That sounds more like a Key error. Are you sure you have put a primary key on that table? If not then EF just uses the whole table as the key essentially

answered Sep 26, 2013 at 17:31

Thewads

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