正在关闭/处置如果你已经关闭的SqlConnection需要一个SqlDataReader的？

问题描述：

我注意到这个问题，但我的问题是有点更具体。

I noticed This question, but my question is a bit more specific.

是否有任何优势，使用

using (SqlConnection conn = new SqlConnection(conStr))
{
     using (SqlCommand command = new SqlCommand())
     {
        // dostuff
     } 
}

而不是

using (SqlConnection conn = new SqlConnection(conStr))
{
     SqlCommand command = new SqlCommand();
     // dostuff
}

显然，不管它，如果你打算运行以上具有相同的连接一个命令，因为关闭一个 SqlDataReader的比关闭和重新打开连接（呼叫 conn.Close（）更高效;康恩。开（）; 也将腾出的连接）

Obviously it does matter if you plan to run more than one command with the same connection, since closing an SqlDataReader is more efficient than closing and reopening a connection (calling conn.Close();conn.Open(); will also free up the connection).

我看到许多人坚持认为没有关闭 SqlDataReader的表示周围留下打开的连接资源，但是如果你不关闭连接并不只适用？

I see many people insist that failure to close the SqlDataReader means leaving open connection resources around, but doesn't that only apply if you don't close the connection?

答

在我看来，有两个规则在这里如下：

In my opinion, there are two rules to follow here:

实现IDisposable的类应被包裹在一个使用块。

您不应该依赖一个类的实现了IDisposable的无视规则1。

也就是说，即使你知道处理连接对象采取了处置及其相关的命令对象的照顾，你不应该依赖这种行为。

That is, even if you know that disposing the connection object took care of disposing its associated command object, you should not rely on this behavior.

顺便说一句，有可能在一个更清洁的方式使用组块：

By the way, it's possible to nest using blocks in a cleaner fashion:

using (SqlConnection conn = new SqlConnection(conStr))
using (SqlCommand command = new SqlCommand())
{
    // dostuff
}

和我会用

SqlCommand command = conn.CreateCommand();

而不是创建一个新的SqlCommand，然后将其与连接相关联。

instead of creating a new SqlCommand and then associating it with the connection.

正在关闭/处置如果你已经关闭的SqlConnection需要一个SqlDataReader的？

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