Question

我已经编写了以下代码来连接到我的数据库。你能不能建议我比这个更好的选择，因为我非常感兴趣的是哪种方式表现更好。以下代码是否实现了Singleton模式？

    public static class DbConnect
    {

        public static DataTable SqlConnection(string query)
        {
            DataTable dt = null;

            using (SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConString"].ConnectionString))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                    {
                        if (cn.State == ConnectionState.Closed)
                        {
                            dt = new DataTable();
                            cn.Open();
                            da.Fill(dt);
                        }
                    }
                    return dt;
                }
            }
        }

    }

Answer 1

类似的是，恕我直言，预期：

添加参数支持
不要隐藏错误：如果连接中断，则应该有例外

所以代码看起来像那样：

      // I've used KeyValuePair for parameters; probably a specialized class will be better 
      public static DataTable SqlConnection(string query, params KeyValuePair<String, Object>[] parameters) {
        using (SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConString"].ConnectionString)) {
          using (SqlCommand cmd = cn.CreateCommand()) {
            cmd.CommandText = query;

            // Parameters, if they're mentioned 
            if (!Object.ReferenceEquals(null, parameters))
              foreach (var prm in parameters)
                cmd.Parameters.AddWithValue(prm.Key, prm.Value);

            using (SqlDataAdapter da = new SqlDataAdapter(cmd)) {
              cn.Open();

              DataTable result = new DataTable();

              da.Fill(result);

              return result;
            }
          }
        }
      }

...

DataTable dt1 = SqlConnection("select 123");
DataTable dt2 = SqlConnection(
                   @"select * 
                      from MyTable 
                     where MyField = @MyParam", 
                   new KeyValuePair<String, Object>("@MyParam", 123));

P.S。代码不是 Singleton 实现，它甚至不是类：只是静态方法。

单例模式代码实现

1 个答案: