1.数据访问基础类(基于OleDb)Access数据库，
    2.得到最大值；是否存在；是否存在（基于OleDbParameter）；
    3.执行SQL语句，返回影响的记录数；执行多条SQL语句，实现数据库事务；
    4.执行带一个存储过程参数的的SQL语句；
    5.向数据库里插入图像格式的字段(和上面情况类似的另一种实例);
    6.执行一条计算查询结果语句，返回查询结果（object）;
    7.执行查询语句，返回OleDbDataReader;
    8.执行查询语句，返回DataSet;
    9.执行SQL语句，返回影响的记录数;
    10.执行多条SQL语句，实现数据库事务;
    11.执行一条计算查询结果语句，返回查询结果（object）;
    12.执行查询语句，返回OleDbDataReader;执行查询语句，返回DataSet;

/// <summary>
/// 编 码 人：苏飞
/// 联系方式：361983679  
/// 更新网站：[url=http://www.sufeinet.com/thread-655-1-1.html]http://www.sufeinet.com/thread-655-1-1.html[/url]
/// </summary>
using System;
using System.Collections;
using System.Collections.Specialized;
using System.Data;
using System.Data.OleDb;
using System.Configuration;
 
namespace Maticsoft.DBUtility
{
    /// <summary>
    /// 数据访问基础类(基于OleDb) 
    /// 可以用户可以修改满足自己项目的需要。
    /// </summary>
    public abstract class DbHelperOleDb
    {
        //数据库连接字符串(web.config来配置)，可以动态更改connectionString支持多数据库.    
        public static string connectionString = "连接字符串";
        public DbHelperOleDb()
        {
        }
 
        #region 公用方法
 
        public static int GetMaxID(string FieldName, string TableName)
        {
            string strsql = "select max(" + FieldName + ")+1 from " + TableName;
            object obj = DbHelperSQL.GetSingle(strsql);
            if (obj == null)
            {
                return 1;
            }
            else
            {
                return int.Parse(obj.ToString());
            }
        }
        public static bool Exists(string strSql)
        {
            object obj = DbHelperSQL.GetSingle(strSql);
            int cmdresult;
            if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
            {
                cmdresult = 0;
            }
            else
            {
                cmdresult = int.Parse(obj.ToString());
            }
            if (cmdresult == 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }
        public static bool Exists(string strSql, params OleDbParameter[] cmdParms)
        {
            object obj = GetSingle(strSql, cmdParms);
            int cmdresult;
            if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
            {
                cmdresult = 0;
            }
            else
            {
                cmdresult = int.Parse(obj.ToString());
            }
            if (cmdresult == 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }
 
        #endregion
 
        #region  执行简单SQL语句
 
        /// <summary>
        /// 执行SQL语句，返回影响的记录数
        /// </summary>
        /// <param name="SQLString">SQL语句</param>
        /// <returns>影响的记录数</returns>
        public static int ExecuteSql(string SQLString)
        {
            using (OleDbConnection connection = new OleDbConnection(connectionString))
            {
                using (OleDbCommand cmd = new OleDbCommand(SQLString, connection))
                {
                    try
                    {
                        connection.Open();
                        int rows = cmd.ExecuteNonQuery();
                        return rows;
                    }
                    catch (System.Data.OleDb.OleDbException E)
                    {
                        connection.Close();
                        throw new Exception(E.Message);
                    }
                }
            }
        }
 
        /// <summary>
        /// 执行多条SQL语句，实现数据库事务。
        /// </summary>
        /// <param name="SQLStringList">多条SQL语句</param>    
        public static void ExecuteSqlTran(ArrayList SQLStringList)
        {
            using (OleDbConnection conn = new OleDbConnection(connectionString))
            {
                conn.Open();
                OleDbCommand cmd = new OleDbCommand();
                cmd.Connection = conn;
                OleDbTransaction tx = conn.BeginTransaction();
                cmd.Transaction = tx;
                try
                {
                    for (int n = 0; n < SQLStringList.Count; n++)
                    {
                        string strsql = SQLStringList[n].ToString();
                        if (strsql.Trim().Length > 1)
                        {
                            cmd.CommandText = strsql;
                            cmd.ExecuteNonQuery();
                        }
                    }
                    tx.Commit();
                }
                catch (System.Data.OleDb.OleDbException E)
                {
                    tx.Rollback();
                    throw new Exception(E.Message);
                }
            }
        }
        /// <summary>
        /// 执行带一个存储过程参数的的SQL语句。
        /// </summary>
        /// <param name="SQLString">SQL语句</param>
        /// <param name="content">参数内容,比如一个字段是格式复杂的文章，有特殊符号，可以通过这个方式添加</param>
        /// <returns>影响的记录数</returns>
        public static int ExecuteSql(string SQLString, string content)
        {
            using (OleDbConnection connection = new OleDbConnection(connectionString))
            {
                OleDbCommand cmd = new OleDbCommand(SQLString, connection);
                System.Data.OleDb.OleDbParameter myParameter = new System.Data.OleDb.OleDbParameter("@content", OleDbType.VarChar);
                myParameter.Value = content;
                cmd.Parameters.Add(myParameter);
                try
                {
                    connection.Open();
                    int rows = cmd.ExecuteNonQuery();
                    return rows;
                }
                catch (System.Data.OleDb.OleDbException E)
                {
                    throw new Exception(E.Message);
                }
                finally
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }
        /// <summary>
        /// 向数据库里插入图像格式的字段(和上面情况类似的另一种实例)
        /// </summary>
        /// <param name="strSQL">SQL语句</param>
        /// <param name="fs">图像字节,数据库的字段类型为image的情况</param>
        /// <returns>影响的记录数</returns>
        public static int ExecuteSqlInsertImg(string strSQL, byte[] fs)
        {
            using (OleDbConnection connection = new OleDbConnection(connectionString))
            {
                OleDbCommand cmd = new OleDbCommand(strSQL, connection);
                System.Data.OleDb.OleDbParameter myParameter = new System.Data.OleDb.OleDbParameter("@fs", OleDbType.Binary);
                myParameter.Value = fs;
                cmd.Parameters.Add(myParameter);
                try
                {
                    connection.Open();
                    int rows = cmd.ExecuteNonQuery();
                    return rows;
                }
                catch (System.Data.OleDb.OleDbException E)
                {
                    throw new Exception(E.Message);
                }
                finally
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }
 
        /// <summary>
        /// 执行一条计算查询结果语句，返回查询结果（object）。
        /// </summary>
        /// <param name="SQLString">计算查询结果语句</param>
        /// <returns>查询结果（object）</returns>
        public static object GetSingle(string SQLString)
        {
            using (OleDbConnection connection = new OleDbConnection(connectionString))
            {
                using (OleDbCommand cmd = new OleDbCommand(SQLString, connection))
                {
                    try
                    {
                        connection.Open();
                        object obj = cmd.ExecuteScalar();
                        if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                        {
                            return null;
                        }
                        else
                        {
                            return obj;
                        }
                    }
                    catch (System.Data.OleDb.OleDbException e)
                    {
                        connection.Close();
                        throw new Exception(e.Message);
                    }
                }
            }
        }
        /// <summary>
        /// 执行查询语句，返回OleDbDataReader
        /// </summary>
        /// <param name="strSQL">查询语句</param>
        /// <returns>OleDbDataReader</returns>
        public static OleDbDataReader ExecuteReader(string strSQL)
        {
            OleDbConnection connection = new OleDbConnection(connectionString);
            OleDbCommand cmd = new OleDbCommand(strSQL, connection);
            try
            {
                connection.Open();
                OleDbDataReader myReader = cmd.ExecuteReader();
                return myReader;
            }
            catch (System.Data.OleDb.OleDbException e)
            {
                throw new Exception(e.Message);
            }
 
        }
        /// <summary>
        /// 执行查询语句，返回DataSet
        /// </summary>
        /// <param name="SQLString">查询语句</param>
        /// <returns>DataSet</returns>
        public static DataSet Query(string SQLString)
        {
            using (OleDbConnection connection = new OleDbConnection(connectionString))
            {
                DataSet ds = new DataSet();
                try
                {
                    connection.Open();
                    OleDbDataAdapter command = new OleDbDataAdapter(SQLString, connection);
                    command.Fill(ds, "ds");
                }
                catch (System.Data.OleDb.OleDbException ex)
                {
                    throw new Exception(ex.Message);
                }
                return ds;
            }
        }
 
 
        #endregion
 
        #region 执行带参数的SQL语句
 
        /// <summary>
        /// 执行SQL语句，返回影响的记录数
        /// </summary>
        /// <param name="SQLString">SQL语句</param>
        /// <returns>影响的记录数</returns>
        public static int ExecuteSql(string SQLString, params OleDbParameter[] cmdParms)
        {
            using (OleDbConnection connection = new OleDbConnection(connectionString))
            {
                using (OleDbCommand cmd = new OleDbCommand())
                {
                    try
                    {
                        PrepareCommand(cmd, connection, null, SQLString, cmdParms);
                        int rows = cmd.ExecuteNonQuery();
                        cmd.Parameters.Clear();
                        return rows;
                    }
                    catch (System.Data.OleDb.OleDbException E)
                    {
                        throw new Exception(E.Message);
                    }
                }
            }
        }
 
 
        /// <summary>
        /// 执行多条SQL语句，实现数据库事务。
        /// </summary>
        /// <param name="SQLStringList">SQL语句的哈希表（key为sql语句，value是该语句的OleDbParameter[]）</param>
        public static void ExecuteSqlTran(Hashtable SQLStringList)
        {
            using (OleDbConnection conn = new OleDbConnection(connectionString))
            {
                conn.Open();
                using (OleDbTransaction trans = conn.BeginTransaction())
                {
                    OleDbCommand cmd = new OleDbCommand();
                    try
                    {
                        //循环
                        foreach (DictionaryEntry myDE in SQLStringList)
                        {
                            string cmdText = myDE.Key.ToString();
                            OleDbParameter[] cmdParms = (OleDbParameter[])myDE.Value;
                            PrepareCommand(cmd, conn, trans, cmdText, cmdParms);
                            int val = cmd.ExecuteNonQuery();
                            cmd.Parameters.Clear();
 
                            trans.Commit();
                        }
                    }
                    catch
                    {
                        trans.Rollback();
                        throw;
                    }
                }
            }
        }
 
 
        /// <summary>
        /// 执行一条计算查询结果语句，返回查询结果（object）。
        /// </summary>
        /// <param name="SQLString">计算查询结果语句</param>
        /// <returns>查询结果（object）</returns>
        public static object GetSingle(string SQLString, params OleDbParameter[] cmdParms)
        {
            using (OleDbConnection connection = new OleDbConnection(connectionString))
            {
                using (OleDbCommand cmd = new OleDbCommand())
                {
                    try
                    {
                        PrepareCommand(cmd, connection, null, SQLString, cmdParms);
                        object obj = cmd.ExecuteScalar();
                        cmd.Parameters.Clear();
                        if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                        {
                            return null;
                        }
                        else
                        {
                            return obj;
                        }
                    }
                    catch (System.Data.OleDb.OleDbException e)
                    {
                        throw new Exception(e.Message);
                    }
                }
            }
        }
 
        /// <summary>
        /// 执行查询语句，返回OleDbDataReader
        /// </summary>
        /// <param name="strSQL">查询语句</param>
        /// <returns>OleDbDataReader</returns>
        public static OleDbDataReader ExecuteReader(string SQLString, params OleDbParameter[] cmdParms)
        {
            OleDbConnection connection = new OleDbConnection(connectionString);
            OleDbCommand cmd = new OleDbCommand();
            try
            {
                PrepareCommand(cmd, connection, null, SQLString, cmdParms);
                OleDbDataReader myReader = cmd.ExecuteReader();
                cmd.Parameters.Clear();
                return myReader;
            }
            catch (System.Data.OleDb.OleDbException e)
            {
                throw new Exception(e.Message);
            }
 
        }
 
        /// <summary>
        /// 执行查询语句，返回DataSet
        /// </summary>
        /// <param name="SQLString">查询语句</param>
        /// <returns>DataSet</returns>
        public static DataSet Query(string SQLString, params OleDbParameter[] cmdParms)
        {
            using (OleDbConnection connection = new OleDbConnection(connectionString))
            {
                OleDbCommand cmd = new OleDbCommand();
                PrepareCommand(cmd, connection, null, SQLString, cmdParms);
                using (OleDbDataAdapter da = new OleDbDataAdapter(cmd))
                {
                    DataSet ds = new DataSet();
                    try
                    {
                        da.Fill(ds, "ds");
                        cmd.Parameters.Clear();
                    }
                    catch (System.Data.OleDb.OleDbException ex)
                    {
                        throw new Exception(ex.Message);
                    }
                    return ds;
                }
            }
        }
 
 
        private static void PrepareCommand(OleDbCommand cmd, OleDbConnection conn, OleDbTransaction trans, string cmdText, OleDbParameter[] cmdParms)
        {
            if (conn.State != ConnectionState.Open)
                conn.Open();
            cmd.Connection = conn;
            cmd.CommandText = cmdText;
            if (trans != null)
                cmd.Transaction = trans;
            cmd.CommandType = CommandType.Text;//cmdType;
            if (cmdParms != null)
            {
                foreach (OleDbParameter parm in cmdParms)
                    cmd.Parameters.Add(parm);
            }
        }
 
        #endregion
 
    }
}