我是否需要关闭并显式处置SQLConnection?

问题描述

限时删除！！

SqlDataReader rdr = null;
con = new SqlConnection(objUtilityDAL.ConnectionString);
using (SqlCommand cmd = con.CreateCommand())
{
    try
    {
        if (con.State != ConnectionState.Open)
            con.Open();
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Parameters.Add(Parameter);
        cmd.CommandText = _query;
        rdr = cmd.ExecuteReader();
    }
    catch (Exception ex)
    {
        throw ex;
    }
}

在上面的代码中，sqlconnection在托管代码内打开.因此，在结束USING范围时，连接对象会自动处置吗?

In this above code, sqlconnection is opened inside the managed code. Hence, will the connection object be disposed automatically upon ending the scope of USING?

推荐答案

创建的每个临时 IDisposable 实例，应处置手动，即使用将它们包装到:

You should Dispose every temporary IDisposable instance you create manually, i.e. wrap them into using:

   // Connecton is IDisposable; we create it
   //   1. manually - new ...
   //   2. for temporary usage (just for the query)
   using (SqlConnection con = new SqlConnection(objUtilityDAL.ConnectionString)) {
     // Check is redundant here: new instance will be closed
     con.Open();

     // Command is IDisposable
     using (SqlCommand cmd = con.CreateCommand()) {
       cmd.CommandType = CommandType.StoredProcedure;
       cmd.Parameters.Add(Parameter);
       cmd.CommandText = _query;

       // Finally, Reader - yes - is IDisposable
       using (SqlDataReader rdr = cmd.ExecuteReader()) {
         // while (rdr.Read()) {...}
       }
     }
   }

请注意

   try {
     ...
   }
   catch (Exception ex) {
     throw ex;
  }

至少是冗余(它没有任何作用，只是抛出了异常，同时失去了堆栈跟踪)，这就是为什么可以将其丢弃

is at least redundant (it does nothing but rethrow the exception, while loosing stack trace) and that's why can be dropped out

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