Linq updating records
Products set, setting Discontinued for each product, and saving changes once. If you were to run SQL Profiler while executing this code, you would see there are a total of 5 SQL statements executed – one to retrieve the data, and four to update each of the four records in the Products table which match the search criteria. Net, I would execute a single update statement: “update products set discontinued=1 where Units In Stock=0 and Units On Order=0”.As the number of out-of-stock products in the Products table grows, the number of SQL statements executed grows.To identify the records at source DB side, I have a column "Emp ID" in OLE DB Source. If you only mark the last that gave you clarification because you misread an earlier post others will be confused.But I dont know how I can use it to update records. Some of us are here to help others and our point to post ratio matters.NET developers to work with relational data using domain-specific objects.” Essentially, it is a layer between your application code and your database which maps your C# classes to database tables.Previous to Entity Framework, you would have used ADO. Updating individual records in Entity Framework is straightforward and relatively simple: create a context, load the record to be updated, update the properties, and save the changes.
You must keep in mind that some databases are designed with constraints and triggers in place that may prevent you from inserting or updating anything.Extended which allows you to (among other features not covered by this article) perform batch Update and Delete statements using a single SQL call. Extended does not yet have a bulk Insert method; however, I have written one based on Paul’s excellent foundation code. Bulk Insert takes a List of objects of type T and executes one or more SQL bulk insert statements. Net, if you are inserting a very large number of records, the Bulk Insert may have to break it up into smaller chunks.The same Discontinue Products method as above could be rewritten as: While this isn’t exactly what we would write if we were doing this by hand, it is far better than what Entity Framework would do on its own. The number of chunks depends on the size (number of fields and data size) of the records you are inserting. from Y” statement, to insert records into one table based on a Select from another set of tables.Net to open a database connection, create a command object, execute a SQL statement, iterate through the results and create your C# class instances (objects) manually. The following method marks a single product as discontinued, based on the product ID: As you can see, I’m using a simple LINQ query to get a single product with a Product ID matching the product ID parameter of the method, setting the Discontinued flag, and saving the changes. Let’s say I wanted to discontinue all products which are out of stock and have no units on order, instead of just one.The overhead of this is a little bit more than if I were using ADO. In this case, I have to execute one database call to retrieve the product, and one database call to update the data. Using only the built-in Entity Framework functionality, I would have to do something like this: This LOOKS pretty simple – I’m iterating through the context. Behind the scenes, Entity Framework is executing one SQL ‘select’ call to retrieve all the products, but when you call Save Changes, it is executing one SQL ‘update’ call per product.