linq-to-sql
I am using LINQ to SQL for the first time on a small project. My tables have Primary Keys that are not identity columns because I am essentially importing from another database. The relationship is a many-to-many with a linking table. Is there a way to tell LINQ to ignore the insert if it is a duplicate?
I have already tried to check the current tables if the object exists and if so, skip to the next but because of the relationships, it makes it difficult.
I can give more details if necessary.
LINQ to SQL only supports 1 to 1 mapping of database tables, views, sprocs and functions available in Microsoft SQL Server. It's a great API to use for quick data access construction to relatively well designed SQL Server databases. LINQ2SQL was first released with C# 3.0 and .Net Framework 3.5.
LINQ to Entities (ADO.Net Entity Framework) is an ORM (Object Relational Mapper) API which allows for a broad definition of object domain models and their relationships to many different ADO.Net data providers. As such, you can mix and match a number of different database vendors, application servers or protocols to design an aggregated mash-up of objects which are constructed from a variety of tables, sources, services, etc. ADO.Net Framework was released with the .Net Framework 3.5 SP1.
This is a good introductory article on MSDN: Introducing LINQ to Relational Data
Go back to the designer and check the relation is set up correctly. Here is one real life example, with BillStateMasters have "CustomerMasters1" property (customers for the state):
Ps. naming is being cleaned up ...
Update 1: You also need to make sure both tables have a primary defined. If the primary key isn't defined on the database (and can't be defined for whatever reason), make sure to define them in the designer. Open the column's properties, and set it as primary key. That said, entity tracking also won't work if you haven't a primary key for the entity, which for deletes means it silently doesn't updates the entity. So, make sure to review all entities and to have them all with a primary key (as I said, if it can't be on the db, then on the designer).
Best Answer
Instead of querying for the whole object what you can do is an Any query...
This will do an optimized query for checking if it exists first.
As far as having LINQ to SQL handle this for you, I'm pretty sure it cannot.