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SqlCommand.ExecuteReader Method

Sends the CommandText to the Connection and builds a SqlDataReader.

Namespace:  System.Data.SqlClient
Assembly:  System.Data (in System.Data.dll)

public SqlDataReader ExecuteReader()

ExceptionCondition
SqlException

An exception occurred while executing the command against a locked row. This exception is not generated when you are using Microsoft .NET Framework version 1.0.

InvalidOperationException

The current state of the connection is closed. ExecuteReader requires an open SqlConnection.

When the CommandType property is set to StoredProcedure, the CommandText property should be set to the name of the stored procedure. The command executes this stored procedure when you call ExecuteReader.

NoteNote:

If a transaction is deadlocked, an exception may not be thrown until Read is called.

When you use versions of SQL Server before SQL Server 2005, while the SqlDataReader is being used, the associated SqlConnection is busy serving the SqlDataReader. While in this state, no other operations can be performed on the SqlConnection other than closing it. This is the case until the Close method of the SqlDataReader is called. Starting with SQL Server 2005, the multiple active result set (MARS) feature allows for multiple actions using the same connection.

If you use ExecuteReader or BeginExecuteReader to access XML data, SQL Server will return any XML results greater than 2,033 characters in length in multiple rows of 2,033 characters each. To avoid this behavior, use ExecuteXmlReader or BeginExecuteXmlReader to read FOR XML queries. For more information, see article Q310378, "PRB: XML Data Is Truncated When You Use SqlDataReader," in the Microsoft Knowledge Base at http://support.microsoft.com.

The following example creates a SqlCommand, and then executes it by passing a string that is a Transact-SQL SELECT statement, and a string to use to connect to the data source.

private static void CreateCommand(string queryString,
    string connectionString)
{
    using (SqlConnection connection = new SqlConnection(
               connectionString))
    {
        connection.Open();

        SqlCommand command = new SqlCommand(queryString, connection);
        SqlDataReader reader = command.ExecuteReader();
        while (reader.Read())
        {
            Console.WriteLine(String.Format("{0}", reader[0]));
        }
    }
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

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