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Introduction to ADO.NET in .NET Generating PDF-417 2d barcode in .NET Introduction to ADO.NET




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Introduction to ADO.NET using barcode printer for visual .net control to generate, create pdf417 image in visual .net applications. Visual Studio .NET Introduction Table 3.7. The Constructors of the DataAdapter Class Constructor S qlDataAdapter() SqlDataAdapter(from) Description Initializes a new instance of a DataAdapter class Initializes a new instance of a DataAdapter class from an existing object of the same type. For ODBC-supp pdf417 for .NET orted data sources, use the OdbcDataAdapter with its associated OdbcCommand and OdbcConnection objects. For Oracle databases, use the OracleDataAdapter with its associated OracleCommand and OracleConnection objects.

. 3.4.4.

1 The C onstructor of the DataAdapter Class The constructor of the DataAdapter class is an overloaded method and has multiple protocols. Two popular protocols are listed in Table 3.7 (an SQL Server Data Provider is used as an example).

The rst constructor is most often used in the most data-driven applications. 3.4.

4.2 The Properties of the DataAdapter Class Some popular properties of the DataAdapter class are listed in Table 3.8.

3.4.4.

3 The Methods of the DataAdapter Class The DataAdapter has more than ten methods available to help develop professional data-driven applications. Table 3.9 lists some of the most often used methods.

Among these methods, Dispose, Fill, FillSchema, and Update are most often used. The Dispose method should be used to release the used DataAdapter after the DataAdapter completes its job. The Fill method should be used to populate a DataSet after the Command object is initialized and ready to be used.

The FillSchema method should be called if you want to add a new DataTable into the DataSet, and the Update method should be used if you want to perform data manipulations such as Insert, Update, and Delete with the database and the DataSet.. Table 3.8. The Public Properties of the DataAdapter Class Property Acce ptChangesDuringFill Description Gets or sets a value indicating whether AcceptChanges is called on a DataRow after it is added to the DataTable during any of the Fill operations. Determines the action to take when incoming data does not have a matching table or column. Determines the action to take when existing DataSet schema does not match incoming data.

Gets a collection that provides the master mapping between a source table and a DataTable.. MissingMappingAction MissingSchemaAction TableMappings 3.4 The Components of ADO.NET Table 3.9. The Public Methods of the DataAdapter Class Method Dispos e Fill FillSchema GetFillParameters ToString Update Description Releases the resources used by the DataAdapter. Adds or refreshes rows in the DataSet to match those in the data source using the DataSet name and creates a DataTable. Adds a DataTable to the speci ed DataSet.

Gets the parameters set by the user when executing an SQL SELECT statement. Returns a String containing the name of the Component, if any. This method should not be overridden.

Calls the respective INSERT, UPDATE, or DELETE statements for each inserted, updated, or deleted row in the speci ed DataSet from a named DataTable.. 3.4.4.

4 The E pdf417 for .NET vents of the DataAdapter Class Two events are available to the DataAdapter class, and these events are listed in Table 3.10.

Before we can complete this section, an example is provided to show readers how to use the DataAdapter to perform data access and data actions between a DataSet and database. Figure 3.13 shows an example of using an SQL Server DataAdapter (assuming that a Connection object, sqlConnection, has been created).

Starting from step A, an SQL SELECT statement string is created with some other new object declarations, such as a new instance of the SqlCommand class, a new object of the SqlDataAdapter class, and a new instance of the DataSet class. The DataSet class will be discussed in the following section. It is used as a table container to hold a collection of data tables.

The Fill method of the DataAdapter class can be used to populate the data tables embedded in the DataSet later. In step B, the SqlCommand object is initialized with the Connection object CommandType and the Command string. The instance of the SqlDataAdapter, sqlDataAdapter, is initialized with the command string and the SqlConnection object in step C.

In step D, the initialized SqlCommand object, sqlCommand, is assigned to the SelectCommand property of the sqlDataAdapter. Also the DataSet is initialized and cleared to make it ready to be lled by executing the Fill method of the sqlDataAdapter to populate the data table in the DataSet later. The Fill method is called to execute a population of data from the Faculty data table into the mapping of that table in the DataSet in step E.

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