ExecuteNonQuery: Connection 属性尚未初始化?

Question

代码:
        SqlConnection conn = con2();
        SqlCommand com = new SqlCommand();
        conn.Open();
        SqlTransaction trans = conn.BeginTransaction();
        com.Transaction = trans;
        try
        {
            com.CommandText = a;
            com.ExecuteNonQuery(); 
            trans.Commit();
        }
        catch (Exception e1)//----e为错误返回数值;
        {
            trans.Rollback();
            conn.Close();
            c = e1.Message; 
        }
        finally
        {
            conn.Close();
        }错误显示:ExecuteNonQuery: Connection 属性尚未初始化,请教各位大虾!怎样解决!

Answer 1

SqlConnection conn = con2(); 
        SqlCommand com = new SqlCommand();
    com.Connection=conn; 
        conn.Open(); 

Answer 2

SqlConnection conn = con2();
        SqlCommand com = new SqlCommand();
com.Connection=conn;
        conn.Open();
        SqlTransaction trans = conn.BeginTransaction();
        com.Transaction = trans;
        try
        {
            com.CommandText = a;
            com.ExecuteNonQuery();
            trans.Commit();
        }
        catch (Exception e1)//----e为错误返回数值;
        {
            trans.Rollback();
            conn.Close();
            c = e1.Message;
        }
        finally
        {
            conn.Close();
        } 

Answer 3

SqlCommand com = new SqlCommand(); 
这个command的sqlconnection没有给它赋值