using System;
using System.Collections;

namespace eBookShop.DAL
{
	/// <summary>
	/// SQLString 的摘要說明。
	/// </summary>
	public class SqlStringConstructor
	{
		/// <summary>
		/// 公有靜態方法，將文本轉換成適合在Sql語句里使用的字符串。
		/// </summary>
		/// <returns>轉換后文本</returns>	
		public static String GetQuotedString(String pStr)
		{
			return ("'" + pStr.Replace("'","''") + "'");
		}

		/// <summary>
		/// 根據條件哈希表,構造SQL語句中的條件子句
		/// </summary>
		/// <param name="conditionHash">條件哈希表</param>
		/// <returns>條件子句</returns>
		public static String GetConditionClause(Hashtable queryItems)
		{

			int Count = 0;
			String Where = "";

			//根據哈希表，循環生成條件子句
			foreach(DictionaryEntry item in queryItems)
			{
				if (Count == 0)
					Where = " Where ";
				else
					Where += " And ";

				//根據查詢列的數據類型，決定是否加單引號
				if(item.Value.GetType().Name=="String" || item.Value.GetType().Name=="DateTime")
				{
					Where += "[" + item.Key.ToString() + "]" 
						+ "Like " 
						+ SqlStringConstructor.GetQuotedString("%"
						+ item.Value.ToString()
						+ "%");
				}
				else
				{
					Where += "[" + item.Key.ToString() + "]" + "= " + item.Value.ToString();
				}
				Count ++;
			}
			return Where;
		}
	}
}