问题描述

我可以有效地使用这种方法吗?

Can I use this approach efficiently?

using(SqlCommand cmd = new SqlCommand("GetSomething", new SqlConnection(Config.ConnectionString))
{
    cmd.Connection.Open();
    // set up parameters and CommandType to StoredProcedure etc. etc.
    cmd.ExecuteNonQuery();
}

我关心的是:SqlCommand 的 Dispose 方法(退出 using 块时调用)是否会关闭底层的 SqlConnection 对象?

My concern is : Will the Dispose method of the SqlCommand (which is called when exiting the using block) close the underlying SqlConnection object or not?

推荐答案

不，处理 SqlCommand 不会影响连接.更好的方法是将 SqlConnection 也包装在 using 块中:

No, Disposing of the SqlCommand will not effect the Connection. A better approach would be to also wrap the SqlConnection in a using block as well:

using (SqlConnection conn = new SqlConnection(connstring))
{
    conn.Open();
    using (SqlCommand cmd = new SqlCommand(cmdstring, conn))
    {
        cmd.ExecuteNonQuery();
    }
}

否则，连接不会因为使用它的命令被释放(也许这就是你想要的?)而改变.但请记住，连接应该也会被处理掉，而且处理起来可能比命令更重要.

Otherwise, the Connection is unchanged by the fact that a Command that was using it was disposed (maybe that is what you want?). But keep in mind, that a Connection should be disposed of as well, and likely more important to dispose of than a command.

我刚刚测试了这个:

SqlConnection conn = new SqlConnection(connstring);
conn.Open();

using (SqlCommand cmd = new SqlCommand("select field from table where fieldid = 1", conn))
{
    Console.WriteLine(cmd.ExecuteScalar().ToString());
}

using (SqlCommand cmd = new SqlCommand("select field from table where fieldid = 2", conn))
{
    Console.WriteLine(cmd.ExecuteScalar().ToString());
}

conn.Dispose();  

退出 using 块时释放第一个命令.连接仍然打开并且对第二个命令有好处.

The first command was disposed when the using block was exited. The connection was still open and good for the second command.

因此，释放命令肯定不会释放它正在使用的连接.

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