微软SQLHelper类详解：中文注释与参数处理

using System;
using System.Data;
using System.Xml;
using System.Data.SqlClient;
using System.Collections;
namespace Book.DAL
{
    /// <summary>
    /// SqlServer数据访问帮助类
    /// </summary>
    public sealed class SqlHelper
    {
        #region 私有构造函数和方法
        private SqlHelper() { }
        /// <summary>
        /// 将SqlParameter参数数组(参数值)分配给SqlCommand命令.
        /// 这个方法将给任何一个参数分配DBNull.Value;
        /// 该操作将阻止默认值的使用.
        /// </summary>
        /// <param name="command">命令名</param>
        /// <param name="commandParameters">SqlParameters数组</param>
        private static void AttachParameters(SqlCommand command, SqlParameter[] commandParameters)
        {
            if (command == null) throw new ArgumentNullException("command");
            if (commandParameters != null)
            {
                foreach (SqlParameter p in commandParameters)
                {
                    if (p != null)
                    {

                        // 检查未分配值的输出参数,将其分配以DBNull.Value.
                        if ((p.Direction == ParameterDirection.InputOutput || p.Direction == ParameterDirection.Input) &&
                            (p.Value == null))
                        {
                            p.Value = DBNull.Value;
                        }
                        command.Parameters.Add(p);
                    }
                }
            }
        }

        /// <summary>
        /// 将DataRow类型的列值分配到SqlParameter参数数组.
        /// </summary>
        /// <param name="commandParameters">要分配值的SqlParameter参数数组</param>
        /// <param name="dataRow">将要分配给存储过程参数的DataRow</param>
        private static void AssignParameterValues(SqlParameter[] commandParameters, DataRow dataRow)
        {
            if ((commandParameters == null) || (dataRow == null))
            {
                return;
            }
            int i = 0;
            // 设置参数值
            foreach (SqlParameter commandParameter in commandParameters)
            {
                // 创建参数名称,如果不存在,只抛出一个异常.
                if (commandParameter.ParameterName == null ||
                    commandParameter.ParameterName.Length <= 1)