DB通用类：Access通用类

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

namespace CommonLib
{
    /// <summary>
    /// 需要实例化的Access存取类
    /// </summary>
    public class DB_Access
    {
        public OleDbConnection Conn;
        public string ConnString;
        public DB_Access(string Dbpath)   
        {   
            ConnString = "Provider=Microsoft.Jet.OleDb.4.0;Data Source=";   
            ConnString += Dbpath;   
            Conn = new OleDbConnection(ConnString);   
            Conn.Open();   
        }
        public OleDbConnection DbConn()
        {
            Conn.Open();
            return Conn;
        }
        public void Close()
        {
            Conn.Close();
        }
        public DataTable SelectToDataTable(string SQL)
        {
            OleDbDataAdapter adapter = new OleDbDataAdapter();
            OleDbCommand command = new OleDbCommand(SQL, Conn);
            adapter.SelectCommand = command;
            DataTable Dt = new DataTable();
            adapter.Fill(Dt);
            return Dt;
        }
        public DataSet SelectToDataSet(string SQL, string subtableName)
        {
            OleDbDataAdapter adapter = new OleDbDataAdapter();
            OleDbCommand command = new OleDbCommand(SQL, Conn);
            adapter.SelectCommand = command;
            DataSet Ds = new DataSet();
            Ds.Tables.Add(subtableName);
            adapter.Fill(Ds, subtableName);
            return Ds;
        }
        public DataSet SelectToDataSet(string SQL, string subtableName, DataSet DataSetName)
        {
            OleDbDataAdapter adapter = new OleDbDataAdapter();
            OleDbCommand command = new OleDbCommand(SQL, Conn);
            adapter.SelectCommand = command;
            DataTable Dt = new DataTable();
            DataSet Ds = new DataSet();
            Ds = DataSetName;
            adapter.Fill(DataSetName, subtableName);
            return Ds;
        }
        public OleDbDataAdapter SelectToOleDbDataAdapter(string SQL)
        {
            OleDbDataAdapter adapter = new OleDbDataAdapter();
            OleDbCommand command = new OleDbCommand(SQL, Conn);
            adapter.SelectCommand = command;
            return adapter;
        } 
        public bool ExecuteSQLNonquery(string SQL)
        {
            OleDbCommand cmd = new OleDbCommand(SQL, Conn);
            try
            {
                cmd.ExecuteNonQuery();
                return true;
            }
            catch
            {
                return false;
            }
        }
    }
    public static class DB_AccessStatic
    {
        /// <summary>
        /// 为执行命令准备参数
        /// </summary>
        /// <param name="cmd">DbCommand 命令</param>
        /// <param name="conn">已经存在的数据库连接</param>
        /// <param name="trans">数据库事物处理</param>
        /// <param name="cmdType">DbCommand命令类型 (存储过程， T-SQL语句， 等等。)</param>
        /// <param name="cmdText">Command text，T-SQL语句 例如 Select * from Products</param>
        /// <param name="cmdParms">返回带参数的命令</param>
        private static void PrepareCommand(OleDbCommand cmd, OleDbConnection conn, OleDbTransaction trans, CommandType cmdType, string cmdText, OleDbParameter[] cmdParms)
        {
            //判断数据库连接状态
            if (conn.State != ConnectionState.Open)
                conn.Open();
            cmd.Connection = conn;
            cmd.CommandText = cmdText;
            //判断是否需要事物处理
            if (trans != null)
                cmd.Transaction = trans;
            cmd.CommandType = cmdType;
            if (cmdParms != null)
            {
                foreach (OleDbParameter parm in cmdParms)
                    cmd.Parameters.Add(parm);
            }
        }

        public static bool ExecuteSQLNonquery(string Dbpath, string strSql, params OleDbParameter[] commandParameters)
        {
            OleDbCommand cmd = new OleDbCommand();
            try
            {
                string ConnString = "Provider=Microsoft.Jet.OleDb.4.0;Data Source=";
                ConnString += Dbpath;
                OleDbConnection conn = new OleDbConnection(ConnString);
                PrepareCommand(cmd, conn, null, CommandType.Text, strSql, commandParameters);
                cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return true;
            }
            catch
            {
                return false;
            }
        }
        /// <summary>
        ///  执行一条返回结果集的OleDbCommand，通过一个已经存在的数据库连接
        /// 使用参数数组提供参数
        /// </summary>
        /// <param name="cmdText">SQL 语句</param>
        /// <returns></returns>
        public static DataTableCollection GetTable(string Dbpath, string strSql, OleDbParameter[] commandParameters)
        {
            string ConnString = "Provider=Microsoft.Jet.OleDb.4.0;Data Source=";
            ConnString += Dbpath;
            return GetTable(ConnString, CommandType.Text, strSql, null);
        }
        /// <summary>
        /// 执行一条返回结果集的OleDbCommand，通过一个已经存在的数据库连接
        /// 使用参数数组提供参数
        /// </summary>
        /// <param name="connecttionString">一个现有的数据库连接</param>
        /// <param name="cmdTye">OleDbCommand命令类型</param>
        /// <param name="cmdText">存储过程的名字或者 SQL 语句</param>
        /// <param name="commandParameters">以数组形式提供DbCommand命令中用到的参数列表</param>
        /// <returns>返回一个表集合(DataTableCollection)表示查询得到的数据集</returns>
        public static DataTableCollection GetTable(string connecttionString, CommandType cmdTye, string cmdText, OleDbParameter[] commandParameters)
        {
            OleDbCommand cmd = new OleDbCommand();
            DataSet ds = new DataSet();
            using (OleDbConnection conn = new OleDbConnection(connecttionString))
            {

                PrepareCommand(cmd, conn, null, CommandType.Text, cmdText, commandParameters);
                OleDbDataAdapter adapter = new OleDbDataAdapter();
                adapter.SelectCommand = cmd;
                adapter.Fill(ds);
            }
            DataTableCollection table = ds.Tables;
            return table;
        }

    }
}