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.net qr code generator free Using Commands in Visual Basic .NET
Using Commands QR Code Maker In Visual Basic .NET Using Barcode generation for VS .NET Control to generate, create Quick Response Code image in .NET applications. www.OnBarcode.comQR Code JIS X 0510 Decoder In VB.NET Using Barcode decoder for .NET Control to read, scan read, scan image in Visual Studio .NET applications. www.OnBarcode.comA command represents any kind of SQL statement made against your database. This gives you powerful application control over your database structure and contents, enabling you to create and delete databases, insert and retrieve data, and manipulate table structures, among other things. A command is implemented via the SqlCommand class and controlled using the SqlCommand.CommandType and SqlCommand.CommandText properties, which are often used in tandem. If you set the CommandType to CommandType.Text, the CommandText property (a string) should contain the SQL statement that you want to execute. If the type is CommandType. StoredProcedure, the CommandText should contain the name of the stored procedure to execute. Finally, if the type is CommandType.Table, the command text should contain the name Barcode Printer In Visual Basic .NET Using Barcode encoder for Visual Studio .NET Control to generate, create Barcode image in VS .NET applications. www.OnBarcode.comLinear 1D Barcode Printer In VB.NET Using Barcode printer for .NET framework Control to generate, create 1D image in VS .NET applications. www.OnBarcode.comCHAPTER 4 s DATA BINDING WITH ASP.NET
Drawing Data Matrix In Visual Basic .NET Using Barcode encoder for .NET framework Control to generate, create Data Matrix 2d barcode image in .NET framework applications. www.OnBarcode.comCode39 Creator In Visual Basic .NET Using Barcode creation for .NET Control to generate, create Code 39 Full ASCII image in Visual Studio .NET applications. www.OnBarcode.comof a table in your database. Executing this type of command will return all records stored in that table. So, for example, if you want to create a query that returns the street address for customers in the AdventureWorks address database who live at postal code 98011, you would use code like this: Barcode Maker In Visual Basic .NET Using Barcode drawer for .NET framework Control to generate, create Barcode image in .NET applications. www.OnBarcode.comUniform Symbology Specification Codabar Maker In Visual Basic .NET Using Barcode generator for .NET Control to generate, create USS Codabar image in Visual Studio .NET applications. www.OnBarcode.comstring connectionString = WebConfigurationManager.ConnectionStrings["AW"].ConnectionString; SqlConnection sqlCon = new SqlConnection(connectionString); SqlCommand sqlComm = new SqlCommand(); sqlComm.Connection = sqlCon; sqlComm.CommandType = CommandType.Text; sqlComm.CommandText = "SELECT AddressLine1 FROM Person.Address " + "WHERE (PostalCode = N'98011')"; Encoding QR Code ISO/IEC18004 In Visual Studio .NET Using Barcode encoder for ASP.NET Control to generate, create QR Code image in ASP.NET applications. www.OnBarcode.comEncoding QR Code ISO/IEC18004 In Java Using Barcode creation for Java Control to generate, create QR Code ISO/IEC18004 image in Java applications. www.OnBarcode.comExecuting the Command
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ExecuteReader: This executes a SELECT query and returns a DataReader object that can be used to provide forward-only read access to your data. ExecuteXmlReader: This is similar to ExecuteReader except that it gives you an XmlReader to access the data. So, executing a command to generate the required feedback is very straightforward. Here s an example of executing the previous query, with the results available via a SqlDataReader: SqlDataReader sRead = sqlComm.ExecuteReader(); CHAPTER 4 s DATA BINDING WITH ASP.NET
In the next section, you ll see how to use this reader to step through the results of the query and access the first line of the returned addresses. Reading the Data
When you execute the previous command, ADO.NET returns a SqlDataReader. This reader is a forward-based read-only cursor that moves forward by one record every time you call its Read method. The Read method returns True if it reads a record and False otherwise. Upon a successful read, it will then load an array of values with the index of the array representing the column name so reader["ColumnName"] will contain this record s value for ColumnName. Thus, we can iterate through the returned result set using a while loop, and upon a successful read, retrieve the result set s data by simply accessing the reader as if it were an array. Listing 4-1 contains the complete code to access the addresses for postal code 98011 in the AdventureWorks database. Listing 4-1. Using Connection, Command, and Reader to Access Data
using using using using using using using using using using using System; System.Data; System.Configuration; System.Web; System.Web.Security; System.Web.UI; System.Web.UI.WebControls; System.Web.UI.WebControls.WebParts; System.Web.UI.HtmlControls; System.Web.Configuration; System.Data.SqlClient; using System.Text; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { string connectionString = WebConfigurationManager.ConnectionStrings["AW"].ConnectionString; StringBuilder strReturn = new StringBuilder(); using (SqlConnection sqlCon = new SqlConnection(connectionString)) { SqlCommand sqlComm = new SqlCommand(); CHAPTER 4 s DATA BINDING WITH ASP.NET
sqlComm.Connection = sqlCon; sqlComm.CommandType = CommandType.Text; sqlComm.CommandText = "SELECT AddressLine1 FROM Person.Address " + "WHERE (PostalCode = N'98011')"; sqlCon.Open(); SqlDataReader sRead = sqlComm.ExecuteReader(); while (sRead.Read()) { strReturn.Append("<li>"); strReturn.Append(sRead["AddressLine1"]); strReturn.Append("</li>"); } } litResults.Text = strReturn.ToString(); } } You can see the results of running this in Figure 4-17.
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