Closing SqlConnection and SqlCommand c#

问题

In my DAL I write queries like this:

using(SQLConnection conn = "connection string here")
{
    SQLCommand cmd = new ("sql query", conn);
    // execute it blah blah
}

Now it just occurred to me that I am not explicitly closing the SQLCommand object. Now I know the 'using' block will take care of the SQLConnection object, but will this also take care of the SQLCommand object? If not than I have a serious problem. I would have to put in the 'using' on the SQLCommand on thousands and thousands of lines of code or do a cmd.Close() on hundreds of methods. Please tell me that if putting in the using or closing the command will provide a better memory management of the web app?

回答1:

No, the using statement will not take care of the command.

You should wrap the commands with using statements as well, since this will properly call Dispose on them:

using(SQLConnection conn = 'connection string here')
{
    using(SQLCommand cmd = new ('sql query', conn))
    {
        //execute it blah blah
    }
}

回答2:

The SqlConnection has no knowledge about the SqlCommand, so you should close it by itself:

using (SqlConnection conn = new SqlConnection("connection string here"))
using (SqlCommand cmd = new SqlCommand("sql query", conn))
{
    // execute it blah blah
}

回答3:

It won't handle the SqlCommand, but the SqlCommand will eventually be handled by the garbage collector. I tend to do the following:

using (SqlConn conn ... )
using (SqlComm comm ... )
{
    conn.Open();
}

Stacking the using statements here will handle both.

来源：https://stackoverflow.com/questions/3370408/closing-sqlconnection-and-sqlcommand-c-sharp