visual basic barcode generator Part III Essential Types in .NET

Encoder qrcode in .NET Part III Essential Types

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I also wrote a solution based on cursors because I was curious about its performance. On the one hand, the cursor can achieve the task using a single ordered scan of the index; on the other hand, a lot of overhead is associated with the record-by-record manipulation of the cursor. You pay overhead per each row that is processed with the cursor that you don t normally pay for set-based manipulation. The cursor solution is quite straightforward: The cursor scans the sequence values once in order and compares each current value with the previous. If the difference between them is greater than one interval, the pair represents a gap. Here s the complete solution s code:

C# DelegateCommand.cs public class DelegateCommand<T> : DelegateCommandBase { public DelegateCommand(Action<T> executeMethod,Func<T,bool> canExecuteMethod): base((o) => executeMethod((T)o), (o) => canExecuteMethod((T)o)) { ... } }

Figure 7-6. The parameters for a Wrapper module define what content is shown and how it is presented.

This type of selection, one that changes the results, is called a projection in LINQ. You will see more of this in the upcoming Transforming Data with LINQ section.

gramming tools that always perform the same operations, no matter what features are supported by the physical data provider. Consider an SQL data source such as a DBMS. SQL Server, Oracle, and DB2 do the same job, but they work in radically different ways. Normalizing their internal and optimized set of features to the abstract functionality exposed by a suite of universal interfaces results in a loss of performance. It also imposes programming overhead because an extra, more abstract layer of code must be used. ADO provides this common programming interface for a variety of DBMSs. ADO.NET comes at things from a different angle. It takes into account the particularity of each DBMS and provides a programming model tailor-made for each one. All .NET data providers share a limited set of common features, but each has unique capabilities. The communication between the user code and the DBMS takes place more directly using ADO.NET. This model works better and faster and is probably clearer to the majority of programmers. But ADO.NET has one snag. Developers must know in advance the data source they re going to access. Generic programming that is, programming in which the same code targets different data sources at different times is hard (but not impossible) to do. You can create a generic command object and a generic data reader, but not a generic data adapter and certainly not a generic connection. However, through the IDbConnection interface, you can work with a connection object without knowing the underlying data source. But you can never create a connection object in a weakly typed manner that is, without the help of the new operator.

A. Incorrect: Setup projects are used to deploy Windows Forms applications, not websites. B. Incorrect: Web Setup Projects package websites in executable setups and Windows

Section 4.3 introduced the WHERE clause, and Section 4.5 explained how you can combine simple and compound conditions in the WHERE clause into more complicated compound conditions by using the logical operators AND, OR, and NOT. This section introduces three new operators you can use in simple conditions: BETWEEN, IN, and LIKE.

Negotiation Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-28