using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace WeighBusiness.Utils.SqlUtils
{
	public class UpdateUtil
	{

		/// <summary>
		/// 更新
		/// </summary>
		/// <param name="table">表</param>
		/// <param name="keyColumn">条件的列名</param>
		/// <param name="keyColumnValue">条件的值</param>
		/// <param name="fieldAndValuePairs">更新的字段及其值。因此必须是偶数对</param>
		/// <returns>更新失败返回false，否则返回true</returns>
		public static bool Update(string table, string keyColumn, string keyColumnValue, params string[] fieldAndValuePairs)
		{
			string updateStr = GetUpdateString(table, keyColumn, keyColumnValue, fieldAndValuePairs);
			if (string.IsNullOrEmpty(updateStr))
				return true;

			return SqlHelperEx.DoExecuteNonQuery(updateStr);
		}

		/// <summary>
		/// 获取更新的sql语句（以换行结尾）
		/// <para>如果没有更新的字段和值，则返回string.Empty</para>
		/// </summary>
		/// <param name="table">表</param>
		/// <param name="keyColumn">条件的列名</param>
		/// <param name="keyColumnValue">条件的值</param>
		/// <param name="fieldAndValuePairs">更新的字段及其值。因此必须是偶数对</param>
		public static string GetUpdateString(string table, string keyColumn, string keyColumnValue, params string[] fieldAndValuePairs)
		{
			string updateStr = string.Empty;
			if (fieldAndValuePairs == null || fieldAndValuePairs.Length == 0)
				return updateStr;
			if (fieldAndValuePairs.Length % 2 == 1)
				throw new ArgumentException("fieldAndValuePairs参数必须为偶数个：分别对应字段及其值");
			string begin = "update " + table + " set ";
			string end = string.Format(" where " + keyColumn + @" = '{0}'
						", keyColumnValue);
			for (int i = 0; i < fieldAndValuePairs.Length; i++) {
				string field = fieldAndValuePairs[i];
				i++;
				string value = fieldAndValuePairs[i];
				updateStr += field + "='" + value + "',";
			}
			updateStr = updateStr.Substring(0, updateStr.Length - 1);
			updateStr = begin + updateStr + end;
			return updateStr;
		}

		/// <summary>
		/// 获取更新的sql语句.
		/// <para>如果没有更新的字段和值，则返回string.Empty</para>
		/// </summary>
		/// <param name="table">表</param>
		/// <param name="keyColumn">条件的列名</param>
		/// <param name="keyColumnValue">条件的值</param>
		/// <param name="fieldAndValuePairs">更新的字段及其值</param>
		/// <returns></returns>
		public static string GetUpdateString(string table, string keyColumn, string keyColumnValue, Dictionary<string, string> fieldAndValuePairs)
		{
			string updateStr = string.Empty;
			if (fieldAndValuePairs == null || fieldAndValuePairs.Count == 0)
				return updateStr;
			string begin = "update " + table + " set ";
			string end = string.Format(" where " + keyColumn + @" = '{0}'", keyColumnValue);
			//for (int i = 0; i < fieldAndValuePairs.Count; i++) {
			//  string field = fieldAndValuePairs[i];
			//  i++;
			//  string value = fieldAndValuePairs[i];
			//  updateStr += field + "='" + value + "',";
			//}
			foreach (var item in fieldAndValuePairs) {
				updateStr += item.Key + "='" + item.Value + "',";
			}
			updateStr = updateStr.Substring(0, updateStr.Length - 1);
			updateStr = begin + updateStr + end;
			return updateStr;
		}

	}
}