Question

Is there a reason to check for null in the last using? Seems to me like it’s most likely not gonna be needed?

using (var connection = new SqlConnection(connectionString))
{
using (var command = new SqlCommand(commandString, connection))
{
    using (var reader = command.ExecuteReader())
    {
      if (reader != null) {
         // Use the reader
      }
    }
   }
}

EDIT:

Should i close reader.Close() and connection.Close() inside the using if i use it like that:

            using (var varConnection = Locale.sqlConnectOneTime(Locale.sqlDataConnectionDetailsDZP))
            using (var sqlWrite = new SqlCommand(preparedCommand, varConnection)) {
                 while (sqlWrite.Read()) {
                  //something to do.
                 }
                 sqlWrite.Close();
                 varConnection.Close();
            }




    public static SqlConnection sqlConnectOneTime(string varSqlConnectionDetails) {
        SqlConnection sqlConnection = new SqlConnection(varSqlConnectionDetails);
        sqlConnect(sqlConnection);
        if (sqlConnection.State == ConnectionState.Open) {
            return sqlConnection;
        }
        return null;
    } 

Is using of close necessary in following example or i can skip those two?
sqlWrite.Close();
varConnection.Close();

With regards,

MadBoy

Answer 1

No, this is not necessary.

But that follows from the definition of ExecuteReader, it is not related to the using clause. ExecuteReader either returns a (non-null) DataReader object or it throws an exception.
The expresion in the if statement will always be true (if it is reached).

And by leaving out the if and all the superfluous brace-pairs you can make this much easier to read:

using (var connection = new SqlConnection(connectionString))
using (var command = new SqlCommand(commandString, connection))
using (var reader = command.ExecuteReader())
{
    // Use the reader
}