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using System;
using System.Data;
using System.Data.OleDb;

/// <summary>
/// 连接ACCESS数据库
/// 命名空间为king
/// 数据库路径为~\App_Data\data.mdb
/// static int count_rs(string st)查询符合条件的纪录条数
/// static int no_rs(string st)执行无返回纪录集的命令
/// </summary>
namespace king
{
    public class oledbcon
    {
        protected OleDbConnection oledbconn;//连接字段
        /// <summary>
        /// 构造函数
        /// </summary>
        public oledbcon()
        {
            try
            {
                oledbconn = new OleDbConnection(@"provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + System.Web.HttpContext.Current.Server.MapPath(@"~\App_Data\data.mdb"));
                oledbconn.Open();
            }
            catch (Exception e)
            {
                throw e;
            }
        }
        ///// <summary>
        ///// 查询符合条件的纪录条数
        ///// </summary>
        ///// <param name="st">要查询的SQL语句</param>
        ///// <returns>符合条件的纪录数</returns>
        public static int count_rs(string st)
        {
            try
            {
                oledbcon mycon = new oledbcon();
                OleDbCommand mycmd = mycon.oledbconn.CreateCommand();
                mycmd.CommandText = st;
                OleDbDataReader rs = mycmd.ExecuteReader();
                int count = 0;
                while (rs.Read())
                {
                    count++;
                }
                rs.Close();
                mycon.oledbconn.Close();
                return count;
            }
            catch (Exception e)
            {
                throw e;
            }
        }
        ///// <summary>
        ///// 执行无返回纪录集的命令
        ///// </summary>
        ///// <param name="st">SQL语句</param>
        ///// <returns>受影响的纪录条数</returns>
        public static int no_rs(string st)
        {
            try
            {
                oledbcon mycon = new oledbcon();
                OleDbCommand mycmd = mycon.oledbconn.CreateCommand();
                mycmd.CommandText = st;
                int count = mycmd.ExecuteNonQuery();
                mycon.oledbconn.Close();
                return count;
            }
            catch (Exception e)
            {
                throw e;
            }
        }
        ///// <summary>
        ///// 返回有纪录的查询
        ///// </summary>
        public class readers
        {
            OleDbDataReader rs;
            oledbcon mycon;
            /// <summary>
            /// 返回字段
            /// </summary>
            /// <param name="value">字段名</param>
            /// <returns>字段值</returns>
            public object this[string value]
            {
                get { return rs[value]; }
            }
            /// <summary>
            /// 返回字段
            /// </summary>
            /// <param name="value">字段序号</param>
            /// <returns>字段值</returns>
            public object this[int value]
            {
                get { return rs[value]; }
            }
            /// <summary>
            /// 检测记录是否唯恐
            /// </summary>
            /// <returns>true,false</returns>
            public Boolean Read()
            {
                if (rs == null)
                {
                    return false;
                }
                else
                {
                    return rs.Read();
                }
            }
            /// <summary>
            /// 构造函数
            /// </summary>
            /// <param name="st">查询命令</param>
            public readers(string st)
            {
                try
                {
                    mycon = new oledbcon();
                    OleDbCommand mycmd = mycon.oledbconn.CreateCommand();
                    mycmd.CommandText = st;
                    rs = mycmd.ExecuteReader();
                }
                catch (Exception e)
                {
                    rs = null;
                    throw e;
                }
            }
            /// <summary>
            /// 析构函数
            /// </summary>
            public void Dispose()
            {
                mycon.oledbconn.Close();
                rs.Close();
            }
        }
       
    }
}