正确的方法在异常事件中关闭数据库连接 [英] Correct way to close database connection in event of exception

问题描述

如果存在异常，以下代码是否使连接断开？

Does the following code leave the connection open if there is an exception?

我使用的是Microsoft SQL精简版数据库。

I am using a Microsoft SQL compact edition database.

try
{
    SqlCeConnection conn = new SqlCeConnection(ConnectionString);

    conn.Open();

    using (SqlCeCommand cmd =
        new SqlCeCommand("SELECT stuff FROM SomeTable", conn))
    {
      // do some stuff
    }

    conn.Close();
}
catch (Exception ex)
{
    ExceptionManager.HandleException(ex);
}

当然一个更好的方法是在尝试之前声明一个连接对象，

Surely a better way would be to declare a connection object before the try, establish a connection inside the try block and close it in a finally block?

 SqlCeConnection conn = null;
 try
 {
    conn = new SqlCeConnection(ConnectionString);

    conn.Open();

    using (SqlCeCommand cmd =
        new SqlCeCommand("SELECT stuff FROM SomeTable", conn))
    {
      // do some stuff
    }
}
catch (Exception ex)
{
    ExceptionManager.HandleException(ex);
}
finally
{
    if( conn != null )  conn.Close();
}

推荐答案

code>使用块的帮助下，您的代码中的code> SqlCeCommand ，您可以对 SqlCeConnection 。

The way you are handling SqlCeCommand in your code with the help of a using block, you could do the same for the SqlCeConnection.

SqlCeConnection conn;
using (conn = new SqlCeConnection(ConnectionString))
{
   conn.Open();
   using (SqlCeCommand cmd = 
       new SqlCeCommand("SELECT stuff FROM SomeTable", conn))
   {
   // do some stuff
   }
}

注意：您可以使用使用对于实现 IDisposable 的类。

Note: You can use a using block for classes that implement IDisposable.

编辑：这与

try
{
    conn = new SqlCeConnection(ConnectionString);
    conn.Open();

    SqlCeCommand cmd = conn.CreateCommand();
    cmd.CommandText = "...";

    cmd.ExecuteNonQuery();
}
finally
{
    conn.Close();
}

ref： http://msdn.microsoft.com/en-us/library/system.data.sqlserverce .sqlceconnection％28VS.80％29.aspx

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