Linq insert doesnt save to DB?

Question

Hello everyone,

Within my code it is possible to put data into a table, but it isn’t saved. The steps that I make: Through a form I want to add a person. When I add a person the gridview shows the added person, but when I have a look at the database data the person isn’t in it. So I believe my query is talking to a temporary database? My database has also a foreign key relationship, but I guess that wouldn’t make any difference..?

public void InsertPersonInAddressBook(string FirstName, string LastName, DateTime BirthDay)
        {            
            Person newPerson = new Person();
            newPerson.FirstName = FirstName;
            newPerson.LastName = LastName;
            newPerson.BirthDay = BirthDay;
            DBPersonDataContext dc = new DBPersonDataContext();
            dc.Persons.InsertOnSubmit(newPerson);
            dc.SubmitChanges();
        }
//And gridview refresh method:
private void GetUsersIntoTable()
        {
            DBPersonDataContext dc = new DBPersonDataContext();
            var q = from a in dc.GetTable<Person>()
                    select new { a.PersonID, a.FirstName, a.LastName };
            dataGridViewPerson.DataSource = q;
        }

Any ideas?

Greetings,

SpaceLama

Answer 1

On 4/25/2012 4:22 PM, SpaceLama wrote:

> Hello everyone,

>

> Within my code it is possible to put data into a table, but it isn’t

> saved. The steps that I make: Through a form I want to add a person.

> When I add a person the gridview shows the added person, but when I have

> a look at the database data the person isn’t in it. So I believe my

> query is talking to a temporary database? My database has also a foreign

> key relationship, but I guess that wouldn’t make any difference..?

>

> public void InsertPersonInAddressBook(string FirstName, string LastName, DateTime BirthDay)

>          {

>              Person newPerson = new Person();

>              newPerson.FirstName = FirstName;

>              newPerson.LastName = LastName;

>              newPerson.BirthDay = BirthDay;

>              DBPersonDataContext dc = new DBPersonDataContext();

>              dc.Persons.InsertOnSubmit(newPerson);

>              dc.SubmitChanges();

>          }

> //And gridview refresh method:

> private void GetUsersIntoTable()

>          {

>              DBPersonDataContext dc = new DBPersonDataContext();

>              var q = from a in dc.GetTable<Person>()

>                      select new { a.PersonID, a.FirstName, a.LastName };

>              dataGridViewPerson.DataSource = q;

>          }

>

> Any ideas?

>

> Greetings,

>

> SpaceLama

>

 

Maybe it's blowing up and you don't know it because you have no

try/catch around the code, which you should always have when accessing a

database.

 

Yeah it does make a difference if there are constrains (relationships)

that you are not honoring during an insert or a delete of a table

row/object ((object) for Linq-2-SQL).

 There is no temp database. The program is not working and there is

something wrong if data is not saving to the database.

 

Answer 2

Are you catching (and ignoring) an exception somewhere?  Just because you can create a new person and submit it doesn't mean that the backing database will accept the change.  In particular, your db may reject it based on a missing or invalid field or required associated record.

The basic code for InsertPersonInAddressBook looks okay, assuming the default constructor for your DBPersonDataContext gets the right connection string with a parameterless constructor.  Maybe that's worth checking too.

I personally don't like creating a new data context every time you want to do a transaction.  I like to create one context and reuse it.

Answer 3

Could u give me some examples?

Thanks for the advice!

Greetings,

Spacelama

Answer 4

99.999% of the time when this happens, it's because you're looking at a different database than your application. Look carefully at the connection string in your config file, and make sure you're looking at that same database. In particular, make sure the file path or server path (depending on what database type you're using) is correct.

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Answer 5

On 4/25/2012 4:55 PM, SpaceLama wrote:

> Could u give me some examples?

>

> Thanks for the advice!

>

> Greetings,

>

> Spacelama

>

 

I suggest that you use and learn form this.

 

http://www.linqpad.net/

 

If Person is linked to Addressbook and Address is linked to Person, then

what you are doing is not right.

 

AdressBook.Persons.Addresses

 

Plural meaning more than one Person (collection) linked to an

AddressBook and more than one Address (collection) to a Person.

 

You just can't add a Person object without the AddressBook object being

in scope, and you cannot add and Address object without the

AddressBook.Persons objects being in scope.

 

You can insert an AdddressBook my itself. But you cannot insert a Person

without the Addressbook object being in play. And you cannot add an

Address object unless the Addressbook.Person objects are in play.

 

Addressbook.Persons.Addresses  with the plural meaning collections with

the object scheme linked together by associations or foreign keys.

 

Answer 6

What do you mean by in play? You cant add a person if you dont add an adress at the same time? Or what are you saying?

Answer 7

On 4/26/2012 3:05 PM, SpaceLama wrote:

> What do you mean by in play? You cant add a person if you dont add an

> adress at the same time? Or what are you saying?

 

You are trying to look at this from a SQL Server standpoint and a T-SQL

standpoint, which you need to toss out the door. Linq-2-SQL is using

this technology behind the scene, but Linq-2-SQL is doing everything for

you as long as you have the object or objects set-up correctly.

 

You need to stop and understand this somewhat, because what you are

using with Linq-2-SQL along with Linq are objects and not data rows and

columns within rows.

 

http://en.wikipedia.org/wiki/Object-oriented_programming

 

Linq is an object oriented programming language. It allows a source such

as a database, array, collections etc etc to be queried with the results

returned as an object or a collection of objects in a tubular form.

 

http://gardenforkingpaths.blogspot.com/2011/12/linq-and-functional-object-oriented.html

 

Linq-2-SQL is really an ORM solution Object Relational Mapping solution.

 

http://en.wikipedia.org/wiki/Object-relational_mapping

 AddressBook, Person and Address are setting on a model, and they are

objects.

 

AddressBook is an object that represents a table called AddressBook.

Person is an object that represents a table called Person.

Address is an object that represents a table called Address.

 An object can be a parent to children objects,  and the parent object

is a container for the children objects.

 

AddressBook object is a container for all Person objects.

 

Person object is a contained for all Address objects.

 

This should have been implemented on the Linq-2-SQL model because of the

foreign-key constraint you had on the Person table pointing to the

AddressBookID it belongs to  in the AddressBook table. The Address

should have a foreign-key to PersonID in the Person table it belongs to.

 

Looking at from an OOP standpoint, which is how Linq-2-SQL is looking at it.

 

AddressBook object should have a Person object and a Person objects

should have Address objects.

 

If doing an add for the first time, you could have this.

 

New Address object with 1 New Person object within the AddressBook

object, and one or more new Address objects within the Person object.

 

Save the AddressBook object that had everything in it (the container),

and Linq-2-SQL will save it all and make the foreign-key associations

itself.

 

You could have just added a single AddressBook object by itself with no

other objects.

 

But to add more Person objects to the AddressBook object, you need to

the get the existing AddressBook object in order to add a new Person

object to it. And then you can save AddressBook, which would have saved

the Person.

 

In order to add more Address records to a Person object, then you will

need to get the existing AddressBook.Person Object in order to add more

Address objects to the Person object and then save Addressbook the

parent container object to a Person object with the Person object being

the parent container object to an Address object.

 You need to stop and understand what you are trying to do here and what

you need to do here in order to accomplish things with Linq-2-SQL,

because there are 3 different OOP technologies you are using here, and

you don't understand them.

 

I suggest you go get yourself a good book on Linq-2-SQL, and if you have

one, the start at page one again and do the examples until you hit the

last page. It will come together for you then, because you don't

understand what you are doing or how to do it.

 HTH

  

 

Answer 8

Hello,

Please follow this link to insert data in database using linq................

http://geekswithblogs.net/dotNETvinz/archive/2010/03/11/inserting-data-to-database-using-linq-to-sql.aspx

http://msdn.microsoft.com/en-us/library/bb386941.aspx

http://stackoverflow.com/questions/3839930/linq-to-sql-insert-data-c-sharp

Regards,

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