SqlHelper改进

 /*改进版*/ //用可变长度参数实现，可输入任意长度参数
        public static DataTable ExecuteDataTable(string sql,params SqlParameter[] para)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                conn.Open();
                using (SqlCommand cmd = new SqlCommand(sql, conn))
                {
                    cmd.Parameters.AddRange(para);
                    SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                    DataSet dataset = new DataSet();
                    adapter.Fill(dataset);
                    return dataset.Tables[0];
                }
            }
        }

//使用方法

DataTable ds = SqlHelper.ExecuteDataTable("select * from T_Student where Name=@Name",new SqlParameter("@Name","wangjia"));