AccessHelper类

 

using System;using System.Collections;using System.Data;using System.Configuration;using System.Data.OleDb;namespace Web{    /// <summary>    ///ACCESSHelper 的摘要说明    /// </summary>    public abstract class AccessHelper    {        //数据库连接字符串        public static string Conn ="Provider= Microsoft.Ace.OleDB.12.0;Data Source="+AppDomain.CurrentDomain.BaseDirectory+"gaorfid.accdb;";        // 用于缓存参数的HASH表        private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());        /// <summary>        ///  给定连接的数据库用假设参数执行一个sql命令（不返回数据集）        /// </summary>        /// <param name="connectionString">一个有效的连接字符串</param>        /// <param name="cmdType">命令类型(存储过程, 文本, 等等)</param>        /// <param name="cmdText">存储过程名称或者sql命令语句</param>        /// <param name="commandParameters">执行命令所用参数的集合</param>        /// <returns>执行命令所影响的行数</returns>        public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params OleDbParameter[] commandParameters)        {            OleDbCommand cmd = new OleDbCommand();            using (OleDbConnection conn = new OleDbConnection(connectionString))            {                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);                int val = cmd.ExecuteNonQuery();                cmd.Parameters.Clear();                return val;            }        }        /// <summary>        /// 用现有的数据库连接执行一个sql命令（不返回数据集）        /// </summary>        /// <param name="connection">一个现有的数据库连接</param>        /// <param name="cmdType">命令类型(存储过程, 文本, 等等)</param>        /// <param name="cmdText">存储过程名称或者sql命令语句</param>        /// <param name="commandParameters">执行命令所用参数的集合</param>        /// <returns>执行命令所影响的行数</returns>        public static int ExecuteNonQuery(OleDbConnection connection, CommandType cmdType, string cmdText, params OleDbParameter[] commandParameters)        {            OleDbCommand cmd = new OleDbCommand();            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);            int val = cmd.ExecuteNonQuery();            cmd.Parameters.Clear();            return val;        }        /// <summary>        ///使用现有的SQL事务执行一个sql命令（不返回数据集）        /// </summary>        /// <remarks>        ///举例:        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new OleDbParameter("@prodid", 24));        /// </remarks>        /// <param name="trans">一个现有的事务</param>        /// <param name="cmdType">命令类型(存储过程, 文本, 等等)</param>        /// <param name="cmdText">存储过程名称或者sql命令语句</param>        /// <param name="commandParameters">执行命令所用参数的集合</param>        /// <returns>执行命令所影响的行数</returns>        public static int ExecuteNonQuery(OleDbTransaction trans, CommandType cmdType, string cmdText, params OleDbParameter[] commandParameters)        {            OleDbCommand cmd = new OleDbCommand();            PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);            int val = cmd.ExecuteNonQuery();            cmd.Parameters.Clear();            return val;        }        /// <summary>        /// 用执行的数据库连接执行一个返回数据集的sql命令        /// </summary>        /// <remarks>        /// 举例:        ///  OleDbDataReader r = ExecuteReader(connString, CommandType.StoredProcedure, "PublishOrders", new OleDbParameter("@prodid", 24));        /// </remarks>        /// <param name="connectionString">一个有效的连接字符串</param>        /// <param name="cmdType">命令类型(存储过程, 文本, 等等)</param>        /// <param name="cmdText">存储过程名称或者sql命令语句</param>        /// <param name="commandParameters">执行命令所用参数的集合</param>        /// <returns>包含结果的读取器</returns>        public static OleDbDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params OleDbParameter[] commandParameters)        {            //创建一个OleDbCommand对象            OleDbCommand cmd = new OleDbCommand();            //创建一个OleDbConnection对象            OleDbConnection conn = new OleDbConnection(connectionString);            //在这里我们用一个try/catch结构执行sql文本命令/存储过程，因为如果这个方法产生一个异常我们要关闭连接，因为没有读取器存在，            //因此commandBehaviour.CloseConnection 就不会执行            try            {                //调用 PrepareCommand 方法，对 OleDbCommand 对象设置参数                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);                //调用 OleDbCommand  的 ExecuteReader 方法                OleDbDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);                //清除参数                cmd.Parameters.Clear();                return reader;            }            catch            {                //关闭连接，抛出异常                conn.Close();                throw;            }        }        /// <summary>        /// 返回DataSet        /// </summary>        /// <param name="connectionString">一个有效的连接字符串</param>        /// <param name="cmdType">命令类型(存储过程, 文本, 等等)</param>        /// <param name="cmdText">存储过程名称或者sql命令语句</param>        /// <param name="commandParameters">执行命令所用参数的集合</param>        /// <returns></returns>        public static DataSet GetDataSet(string connectionString, CommandType cmdType, string cmdText, params OleDbParameter[] commandParameters)        {            //创建一个OleDbCommand对象            OleDbCommand cmd = new OleDbCommand();            //创建一个OleDbConnection对象            OleDbConnection conn = new OleDbConnection(connectionString);            //在这里我们用一个try/catch结构执行sql文本命令/存储过程，因为如果这个方法产生一个异常我们要关闭连接，因为没有读取器存在，            try            {                //调用 PrepareCommand 方法，对 OleDbCommand 对象设置参数                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);                //调用 OleDbCommand  的 ExecuteReader 方法                OleDbDataAdapter adapter = new OleDbDataAdapter();                adapter.SelectCommand = cmd;                DataSet ds = new DataSet();                adapter.Fill(ds);                //清除参数                cmd.Parameters.Clear();                conn.Close();                return ds;            }            catch (Exception e)            {                throw e;            }        }        /// <summary>        /// 用指定的数据库连接字符串执行一个命令并返回一个数据集的第一列        /// </summary>        /// <remarks>        ///例如:        ///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new OleDbParameter("@prodid", 24));        /// </remarks>        ///<param name="connectionString">一个有效的连接字符串</param>        /// <param name="cmdType">命令类型(存储过程, 文本, 等等)</param>        /// <param name="cmdText">存储过程名称或者sql命令语句</param>        /// <param name="commandParameters">执行命令所用参数的集合</param>        /// <returns>用 Convert.To{Type}把类型转换为想要的 </returns>        public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params OleDbParameter[] commandParameters)        {            OleDbCommand cmd = new OleDbCommand();            using (OleDbConnection connection = new OleDbConnection(connectionString))            {                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);                object val = cmd.ExecuteScalar();                cmd.Parameters.Clear();                return val;            }        }        /// <summary>        /// 用指定的数据库连接执行一个命令并返回一个数据集的第一列        /// </summary>        /// <remarks>        /// 例如:        ///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new OleDbParameter("@prodid", 24));        /// </remarks>        /// <param name="connection">一个存在的数据库连接</param>        /// <param name="cmdType">命令类型(存储过程, 文本, 等等)</param>        /// <param name="cmdText">存储过程名称或者sql命令语句</param>        /// <param name="commandParameters">执行命令所用参数的集合</param>        /// <returns>用 Convert.To{Type}把类型转换为想要的 </returns>        public static object ExecuteScalar(OleDbConnection connection, CommandType cmdType, string cmdText, params OleDbParameter[] commandParameters)        {            OleDbCommand cmd = new OleDbCommand();            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);            object val = cmd.ExecuteScalar();            cmd.Parameters.Clear();            return val;        }        /// <summary>        /// 将参数集合添加到缓存        /// </summary>        /// <param name="cacheKey">添加到缓存的变量</param>        /// <param name="commandParameters">一个将要添加到缓存的sql参数集合</param>        public static void CacheParameters(string cacheKey, params OleDbParameter[] commandParameters)        {            parmCache[cacheKey] = commandParameters;        }        /// <summary>        /// 找回缓存参数集合        /// </summary>        /// <param name="cacheKey">用于找回参数的关键字</param>        /// <returns>缓存的参数集合</returns>        public static OleDbParameter[] GetCachedParameters(string cacheKey)        {            OleDbParameter[] cachedParms = (OleDbParameter[])parmCache[cacheKey];            if (cachedParms == null)                return null;            OleDbParameter[] clonedParms = new OleDbParameter[cachedParms.Length];            for (int i = 0, j = cachedParms.Length; i < j; i++)                clonedParms[i] = (OleDbParameter)((ICloneable)cachedParms[i]).Clone();            return clonedParms;        }        /// <summary>        /// 准备执行一个命令        /// </summary>        /// <param name="cmd">sql命令</param>        /// <param name="conn">OleDb连接</param>        /// <param name="trans">OleDb事务</param>        /// <param name="cmdType">命令类型例如存储过程或者文本</param>        /// <param name="cmdText">命令文本,例如:Select * from Products</param>        /// <param name="cmdParms">执行命令的参数</param>        private static void PrepareCommand(OleDbCommand cmd, OleDbConnection conn, OleDbTransaction trans, CommandType cmdType, 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 = cmdType;            if (cmdParms != null)            {                foreach (OleDbParameter parm in cmdParms)                    cmd.Parameters.Add(parm);            }        }    }}