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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]));
        }
    }
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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