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We began this chapter by reviewing VB .NET’s structured error handling. Then we discussed the sources of exceptions in ADO.NET database applications.

You saw how to handle exceptions thrown by the CLR and by the database. In particular, you learned how to handle both single and multiple database exceptions with the System.Data.SqlClient.SqlException class.

In the next chapter, you’ll look at transactions and how to maintain database integrity when multiple users are working concurrently.

In this chapter you took some significant steps in furthering your understanding of relational databases. The ability to establish relationships between tables gives you a lot of flexibility and power. As you worked through the chapter, you did the following:

In the next chapter you’ll move from SQL statements to revisit SQL queries and experiment with more advanced query facilities.

In this chapter, you learned how to construct more sophisticated queries using the following SQL features:

You’ve now looked in closer detail at all the elements of a database that were used in previous chapters. As a result, the next few chapters will sail you into uncharted database territory. You’ll start by learning about two more important database objects that build upon your knowledge of tables and SQL queries: views and stored procedures.

In this chapter you learned about views and stored procedures. First we discussed views, in particular how to create them and use them like tables. You used both Server Explorer and VB .NET to experiment with views.

Most of the chapter was dedicated to stored procedures, the various ways they accept input and produce output, and how to call stored procedures and handle what they return in VB .NET. In particular, you learned how to create appropriate command parameters and when to use the ExecuteReader, ExecuteScalar, and ExecuteNonQuery when dealing with stored procedures.

Along the way you practiced many techniques covered in earlier chapters. We didn’t cover handling multiple result sets from stored procedures, because you use the same technique presented in Chapter 7. Applying this to a stored procedure would be an excellent exercise and really test your mastery of the concepts presented in this chapter.

Next we’ll return to some database concepts: indexes and constraints.

In this chapter, we discussed various ways to fetch data automatically from an external data source, be it an array, a database, a dataset, or any data structure capable of storing and retrieving data. You also saw how Windows Forms controls offer built-in support for binding to data sources and retrieving and modifying them. The main topics covered in this chapter were as follows:

In the next chapter, you’ll meet the Web equivalents to a lot of these controls, as you look into ASP.NET and the world of Web Forms.

In this chapter we covered the basic security concepts and facilities for MSDE and SQL Server.

Other RDBMSs provide similar facilities, and all of them support standard SQL’s GRANT and REVOKE statements. However, the specifics differ, so consult your database documentation when planning and implementing database security.

This chapter began with a quick overview of XML and its advantages and disadvantages. Then, after analyzing the basic elements of an XML document, you used Visual Studio .NET to construct an XML document and generate its schema automatically. Next, we discussed support for XML in ADO.NET; you read an XML document into a DataSet and wrote an XML document from a DataSet. Finally, you looked at application configuration files, an important application of XML in database programs.

XML is a huge topic and we’ve just skimmed the surface here. But this chapter is a good foundation from which you can develop your experience with this standard for describing and storing data.

In the next chapter, you’ll look at handling errors arising from ADO.NET code and the database itself.

We began this chapter by reviewing VB .NET’s structured error handling. Then we discussed the sources of exceptions in ADO.NET database applications.

You saw how to handle exceptions thrown by the CLR and by the database. In particular, you learned how to handle both single and multiple database exceptions with the System.Data.SqlClient.SqlException class.

In the next chapter, you’ll look at transactions and how to maintain database integrity when multiple users are working concurrently.

In this chapter you learned what transactions are and when to use them. You learned about the ACID properties of transactions and that transactions either complete successfully and are committed or fail at some point and are rolled back so the database is left in its original state before the transaction began. You then learned that you can write database transactions in SQL and in VB .NET. You also learned about concurrency and locks; these are key topics in the realm of transactions, as without them you would have no guarantee that information held in databases would remain consistent with the real world.

In this chapter, you looked at connections using various data providers. You learned about connection strings and connection string parameters, and you saw how to open and close connections.

You examined different security options for SQL Server and other data sources and also saw how to display information about the connection after it’s established, using the properties of a connection.

You saw how to handle exceptions generated by connection errors and learned to close the connection in the finally block of the exception handler to ensure that the connection is closed in all cases.

Finally, you looked at specific examples of connecting to different data sources, including the following:

In the next chapter, you’ll look at ADO.NET and see how to use them to access data.