訪問Access數據庫

using System;
using System.IO; 
using System.Collections;
using System.Data; 
using System.Data.OleDb;   
namespace Exam_Manage.DAL
{
    /// <summary>
    /// 試題數據訪問基礎類
    /// </summary>
    public abstract class DbSQL
    {
        public DbSQL()
        {
        }
        protected static string connectionString=@"provider=microsoft.jet.oledb.4.0; " + "Data Source= " +Directory.GetCurrentDirectory() + @"mdbdb.mdb";
        
        #region  執行簡單SQL語句

        /// <summary>
        /// 執行SQL語句，返回影響的記錄數
        /// </summary>
        /// <param name="SQLString">SQL語句</param>
        /// <returns>影響的記錄數</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>
        /// 執行多條SQL語句，實現數據庫事務。
        /// </summary>
        /// <param name="SQLStringList">多條SQL語句</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>
        /// 執行帶一個存儲過程參數的的SQL語句。
        /// </summary>
        /// <param name="SQLString">SQL語句</param>
        /// <param name="content">參數內容,比如一個字段是格式複雜的文章，有特殊符號，可以通過這個方式添加</param>
        /// <returns>影響的記錄數</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>
        /// 執行一條計算查詢結果語句，返回查詢結果（object）。
        /// </summary>
        /// <param name="SQLString">計算查詢結果語句</param>
        /// <returns>查詢結果（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>
        /// 執行查詢語句，返回SqlDataReader
        /// </summary>
        /// <param name="strSQL">查詢語句</param>
        /// <returns>SqlDataReader</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>
        /// 執行查詢語句，返回DataSet
        /// </summary>
        /// <param name="SQLString">查詢語句</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 執行帶參數的SQL語句

        /// <summary>
        /// 執行SQL語句，返回影響的記錄數
        /// </summary>
        /// <param name="SQLString">SQL語句</param>
        /// <returns>影響的記錄數</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>
        /// 執行一條計算查詢結果語句，返回查詢結果（object）。
        /// </summary>
        /// <param name="SQLString">計算查詢結果語句</param>
        /// <returns>查詢結果（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>
        /// 執行查詢語句，返回SqlDataReader
        /// </summary>
        /// <param name="strSQL">查詢語句</param>
        /// <returns>SqlDataReader</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>
        /// 執行查詢語句，返回DataSet
        /// </summary>
        /// <param name="SQLString">查詢語句</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    

    }

    }