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In Lesson 4, we learned about how to read data quickly an let go of the connection with the Sql Data Reader.
This Lesson shows how to accomplish something in-between Sql Connection and Sql Data Reader interaction by using the Data Set and Sql Data Adapter objects.
I get a null reference exception as soon as I start modifying the data in the rows. I don't doubt that I don't have the Data Table wired in correctly yet, but I have to get past this problem to finish troubleshooting the method.
This is confusing, since I'm using the same SELECT query here as in the object's data-retrieval method.
A Data Set is an in-memory data store that can hold numerous tables.
Data Sets only hold data and do not interact with a data source.
Fill(ds, "Orders"); // start the transaction Sql Transaction tran = conn.
In Lesson 3, we discussed a fully connected mode of operation for interacting with a data source by using the Sql Command object.It is the Sql Data Adapter that manages connections with the data source and gives us disconnected behavior.The Sql Data Adapter opens a connection only when required and closes it as soon as it has performed its task.String conn String = "Data Source=(local); Integrated security=SSPI;" "Initial Catalog=Northwind;"; String sql Select = "SELECT * FROM Orders"; Sql Connection conn = new Sql Connection(conn String); conn. Open(); Sql Data Adapter da = new Sql Data Adapter(sql Select, conn); Data Set ds = new Data Set(); // define update logic for the data adapter // load data from the data source into the Data Set da.