using System;
using System.Data;
using System.Configuration;
using System.Data.OleDb;
using ahwildlife.Utils;


/// <summary>
/// AccessHelper 的摘要说明
/// </summary>
public class AccessHelper
{
    #region 变量
    protected static OleDbConnection conn = new OleDbConnection();
    protected static OleDbCommand comm = new OleDbCommand();
    protected static string connectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=ahwildlife.mdb;Persist Security Info=False;Jet OLEDB:Database Password=sa;";
    #endregion

    #region 构造函数
    /// <summary>
    /// 构造函数
    /// </summary>
    public AccessHelper()
    {

    }
    #endregion

    #region 打开数据库
    /// <summary>
    /// 打开数据库
    /// </summary>
    private static void openConnection()
    {
        if (conn.State == ConnectionState.Closed)
        {
            conn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=ahwildlife.mdb;Persist Security Info=False;Jet OLEDB:Database Password=sa;";
            comm.Connection = conn;
            try
            {
                conn.Open();
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
        }
    }
    #endregion

    #region 关闭数据库
    /// <summary>
    /// 关闭数据库
    /// </summary>
    private static void closeConnection()
    {
        if (conn.State == ConnectionState.Open)
        {
            conn.Close();
            conn.Dispose();
            comm.Dispose();
        }
    }
    #endregion

    #region 执行sql语句
    /// <summary>
    /// 执行sql语句
    /// </summary>
    public static void ExecuteSql(string sqlstr)
    {
        try
        {
            openConnection();
            comm.CommandType = CommandType.Text;
            comm.CommandText = sqlstr;
            comm.ExecuteNonQuery();
        }
        catch (Exception ex)
        {
            throw new Exception(ex.Message);
        }
        finally
        {
            closeConnection();
        }
    }
    #endregion

    #region 返回指定sql语句的OleDbDataReader对象,使用时请注意关闭这个对象。
    /// <summary>
    /// 返回指定sql语句的OleDbDataReader对象,使用时请注意关闭这个对象。
    /// </summary>
    public static OleDbDataReader DataReader(string sqlstr)
    {
        OleDbDataReader dr = null;
        try
        {
            openConnection();
            comm.CommandText = sqlstr;
            comm.CommandType = CommandType.Text;

            dr = comm.ExecuteReader(CommandBehavior.CloseConnection);
        }
        catch
        {
            try
            {
                dr.Close();
                closeConnection();
            }
            catch { }
        }
        return dr;
    }
    #endregion

    #region 返回指定sql语句的OleDbDataReader对象,使用时请注意关闭
    /// <summary>
    /// 返回指定sql语句的OleDbDataReader对象,使用时请注意关闭
    /// </summary>
    public static void DataReader(string sqlstr, ref OleDbDataReader dr)
    {
        try
        {
            openConnection();
            comm.CommandText = sqlstr;
            comm.CommandType = CommandType.Text;
            dr = comm.ExecuteReader(CommandBehavior.CloseConnection);
        }
        catch
        {
            try
            {
                if (dr != null && !dr.IsClosed)
                    dr.Close();
            }
            catch
            {
            }
            finally
            {
                closeConnection();
            }
        }
    }
    #endregion

    #region 返回指定sql语句的DataSet
    /// <summary>
    /// 返回指定sql语句的DataSet
    /// </summary>
    /// <param name="sqlstr"></param>
    /// <returns></returns>
    public static DataSet DataSet(string sqlstr)
    {
        DataSet ds = new DataSet();
        OleDbDataAdapter da = new OleDbDataAdapter();
        try
        {
            openConnection();
            comm.CommandType = CommandType.Text;
            comm.CommandText = sqlstr;
            da.SelectCommand = comm;
            da.Fill(ds);

        }
        catch (Exception e)
        {
            throw new Exception(e.Message);
        }
        finally
        {
            closeConnection();
        }
        return ds;
    }
    #endregion

    #region 返回指定sql语句的DataSet
    /// <summary>
    /// 返回指定sql语句的DataSet
    /// </summary>
    /// <param name="sqlstr"></param>
    /// <param name="ds"></param>
    public static void DataSet(string sqlstr, ref DataSet ds)
    {
        OleDbDataAdapter da = new OleDbDataAdapter();
        try
        {
            openConnection();
            comm.CommandType = CommandType.Text;
            comm.CommandText = sqlstr;
            da.SelectCommand = comm;
            da.Fill(ds);
        }
        catch (Exception e)
        {
            throw new Exception(e.Message);
        }
        finally
        {
            closeConnection();
        }
    }
    #endregion

    #region 返回指定sql语句的DataTable
    /// <summary>
    /// 返回指定sql语句的DataTable
    /// </summary>
    /// <param name="sqlstr"></param>
    /// <returns></returns>
    public static DataTable DataTable(string sqlstr)
    {
        DataTable dt = Common.GetDataTableCache(sqlstr);//读缓存
        if (dt != null)
        {
            return dt.Copy();
        }
        else
        {
            dt = new DataTable();
            OleDbDataAdapter da = new OleDbDataAdapter();
            try
            {
                using (OleDbConnection conn = new OleDbConnection())
                {
                    conn.ConnectionString = connectionString;
                    conn.Open();
                    using (OleDbCommand comm = new OleDbCommand())
                    {
                        comm.Connection = conn;
                        comm.CommandType = CommandType.Text;
                        comm.CommandText = sqlstr;
                        da.SelectCommand = comm;
                        da.Fill(dt);
                    }
                }
            }
            catch (Exception e)
            {
                throw new Exception(e.Message);
            }
            finally
            {
                closeConnection();
            }
            Common.InsertDataTableCache(sqlstr, dt);//添加缓存
            return dt.Copy();
        }
    }
    #endregion

    #region 返回指定sql语句的DataTable
    /// <summary>
    /// 返回指定sql语句的DataTable
    /// </summary>
    public static void DataTable(string sqlstr, ref DataTable dt)
    {
        OleDbDataAdapter da = new OleDbDataAdapter();
        try
        {
            openConnection();
            comm.CommandType = CommandType.Text;
            comm.CommandText = sqlstr;
            da.SelectCommand = comm;
            da.Fill(dt);
        }
        catch (Exception e)
        {
            throw new Exception(e.Message);
        }
        finally
        {
            closeConnection();
        }
    }
    #endregion

    #region 返回指定sql语句的DataView
    /// <summary>
    /// 返回指定sql语句的DataView
    /// </summary>
    /// <param name="sqlstr"></param>
    /// <returns></returns>
    public static DataView DataView(string sqlstr)
    {
        OleDbDataAdapter da = new OleDbDataAdapter();
        DataView dv = new DataView();
        DataSet ds = new DataSet();
        try
        {
            openConnection();
            comm.CommandType = CommandType.Text;
            comm.CommandText = sqlstr;
            da.SelectCommand = comm;
            da.Fill(ds);
            dv = ds.Tables[0].DefaultView;
        }
        catch (Exception e)
        {
            throw new Exception(e.Message);
        }
        finally
        {
            closeConnection();
        }
        return dv;
    }
    #endregion

}