C# SqlDataReader 关闭方法

Question

Which of these methods is better for closing SqlDataReader :

 SqlDataReader reader = comm.ExecuteReader();

 while (reader.Read())
 {
 }
 reader.Close();
 reader.Dispose();

or

SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection);
while (reader.Read())
{
}

or there are another further closing methods?

Answer 1

The correct way of handling this is the using statement:

using(SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection)) {
    while (reader.Read())
    { 

    }
}

This way the object gets disposed correctly (and you don't need to call Close() ).

Answer 2

A using statement is the best practice in such situations from my experience. It makes sure the connection is properly closed even if an exception happens somewhere inside.

using (SqlDataReader reader = comm.ExecuteReader())
{
    while (reader.Read())
    {
        //Do stuff...
    }
}

Of course you could do the same with a try { } finally { } , which is what the using statement does internally. I found it's generally a good idea to get in the habit of always handling readers via the using statement to avoid the possibility of leaked connections.

Answer 3

Use first scenario if you work with reader within one method and second one if you pass reader as return value (not within one scope).

Answer 4

the doc you need is this one: http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldatareader.close.aspx

To quote: "You must explicitly call the Close method when you are through using the SqlDataReader to use the associated SqlConnection for any other purpose."