Instrucción Using

Hola, en el código de abajo se utiliza la instrucción using,

Está bien usado?
La instrucción using sirve para liberar recursos, pero esto no se está
haciendo ya en la instrucción finally?

Muchas gracias



public static int CheckSequenceNumber(string idBBDD, string sequenceNum,
string fileName)
{
string text1 = ConfigurationSettings.AppSettings.Get("ConnStr");
int num1 = 0;
using (SqlConnection connection1 = new SqlConnection(text1))
{
SqlCommand command1 = new SqlCommand();
command1.CommandType = CommandType.StoredProcedure;
command1.Connection = connection1;
command1.CommandText = "checkSequenceNumberDB";
SqlParameter parameter1 = command1.Parameters.Add("@databaseId",
SqlDbType.Int);
parameter1.Direction = ParameterDirection.Input;
SqlParameter parameter2 =
command1.Parameters.Add("@SequenceNumber", SqlDbType.Int);
parameter2.Direction = ParameterDirection.Input;
SqlParameter parameter3 = command1.Parameters.Add("@fileName",
SqlDbType.VarChar, 60);
parameter3.Direction = ParameterDirection.Input;
SqlParameter parameter4 = command1.Parameters.Add("@state",
SqlDbType.Int);
parameter4.Direction = ParameterDirection.Output;
parameter1.Value = Convert.ToInt32(idBBDD);
parameter2.Value = Convert.ToInt32(sequenceNum);
parameter3.Value = fileName;
try
{
connection1.Open();
command1.ExecuteNonQuery();
return Convert.ToInt32(parameter4.Value);
}
catch (Exception exception1)
{
throw new Exception("Details :" + exception1.Message,
exception1);
}
finally
{
connection1.Close();
}
}
return num1;
}