CommandBehavior.SingleRow in C#

In ADO.NET with C#, CommandBehavior.SingleRow is an option that can be applied when executing a database query using a DataReader. This option is used to optimize the retrieval of data when you expect to receive only a single row of data or when you want to improve performance by getting less information from the database. When CommandBehavior.SingleRow is set, the DataReader will only read the first row of the result set and then close itself automatically, freeing up database resources more efficiently.

Here's a simple explanation and a complete source code example with expected output:

using System;
using System.Data;
using System.Data.SqlClient;

class Program
{
    static void Main()
    {
        string connectionString = "Server=your_server_name;Database=your_database_name;User Id=your_username;Password=your_password;";

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            string sqlQuery = "SELECT FirstName, LastName FROM Customers WHERE CustomerID = 1";
            using (SqlCommand command = new SqlCommand(sqlQuery, connection))
            {
                // Use CommandBehavior.SingleRow to optimize for a single row
                using (SqlDataReader reader = command.ExecuteReader(CommandBehavior.SingleRow))
                {
                    if (reader.Read())
                    {
                        string firstName = reader["FirstName"].ToString();
                        string lastName = reader["LastName"].ToString();

                        Console.WriteLine($"First Name: {firstName}, Last Name: {lastName}");
                    }
                    else
                    {
                        Console.WriteLine("No matching record found.");
                    }
                }
            }
        }
    }
}

Explanation of the code:

1. We establish a database connection by providing the connection string, which includes server name, database name, username, and password.
2. Inside a using block, we create a SqlConnection object and open the database connection.
3. We define a SQL query that selects the first name and last name of a customer with a specific CustomerID (in this case, CustomerID = 1).
4. We create a SqlCommand object with the SQL query and the database connection.
5. By using ExecuteReader(CommandBehavior.SingleRow), we specify that we only want to read a single row of data, and the DataReader will automatically close itself after fetching that row.
6. Inside the if (reader.Read()) block, we check if a row is successfully read, and if so, we retrieve the first name and last name of the customer and display them. If no row is found, we display a message indicating that no matching record was found.

Expected Output (assuming a matching record exists in the database)

First Name: John, Last Name: Doe

In this example, CommandBehavior.SingleRow is used to optimize the database query for fetching a single row of data efficiently. It is especially useful when you know you only need one row of data from a query result.