C# Access 數據庫 操作

using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.OleDb;
using System.Windows.Forms;

namespace MyProjectDAL
{
    public class AccessDB
    {
        private OleDbConnection connection;
        private string connectionString;

        //構造函數
        public AccessDB()
        {
            string path = Application.ExecutablePath;
            FileInfo exeInfo = new FileInfo(path);
            path = exeInfo.DirectoryName + "\\";
            connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path + "user data\\database\\MyProject.mdb";
            connection = new OleDbConnection(connectionString);
        }

        //打開連接
        private bool OpenConnection()
        {
            try
            {
                connection.Open();
                return true;
            }
            catch (OleDbException ex)
            {
                MessageBox.Show("數據庫連接失敗 ErrorCode: " + (ex.ErrorCode).ToString());
                return false;
            }
        }

        //關閉連接
        private bool CloseConnection()
        {
            try
            {
                connection.Close();
                return true;
            }
            catch (OleDbException ex)
            {
                MessageBox.Show("關閉數據庫失敗 ErrorCode: " + (ex.ErrorCode).ToString());
                return false;
            }
        }

        //執行插入語句
        public bool Insert(String strInsert)
        {
            string query = strInsert;
            try
            {
                if (this.OpenConnection() == true)
                {
                    OleDbCommand cmd = new OleDbCommand(query, connection);
                    cmd.ExecuteNonQuery();
                    this.CloseConnection();
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch (OleDbException ex)
            {
                MessageBox.Show("數據庫操作失敗 ErrorCode: " + (ex.ErrorCode).ToString());
                return false;
            }
        }

        //執行更新語句
        public bool Update(String strUpdate)
        {
            string query = strUpdate;
            try
            {
                if (this.OpenConnection() == true)
                {
                    OleDbCommand cmd = new OleDbCommand();
                    cmd.CommandText = query;
                    cmd.Connection = connection;
                    cmd.ExecuteNonQuery();
                    this.CloseConnection();
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch (OleDbException ex)
            {
                MessageBox.Show("數據庫更新失敗 ErrorCode: " + (ex.ErrorCode).ToString());
                return false;
            }
        }

        //執行刪除語句
        public bool Delete(String sql)
        {
            string query = sql;
            try
            {
                if (this.OpenConnection() == true)
                {
                    OleDbCommand cmd = new OleDbCommand(query, connection);
                    cmd.ExecuteNonQuery();
                    this.CloseConnection();
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch (OleDbException ex)
            {
                MessageBox.Show("數據庫操作失敗 ErrorCode: " + (ex.ErrorCode).ToString());
                return false;
            }
        }

        //執行查詢語句
        public DataTable Query(string strQuery)
        {
            string query = strQuery;
            DataTable dt = new DataTable();
            try{
                if (this.OpenConnection() == true)
                {
                    OleDbDataAdapter da = new OleDbDataAdapter(query, connection);
                    da.Fill(dt);
                 }
                this.CloseConnection();
            }
            catch (OleDbException ex)
            {
                MessageBox.Show("數據庫操作失敗 ErrorCode: " + (ex.ErrorCode).ToString());
            }
            return dt;  
        }

        //執行查詢計數語句
        public int Count(string strCount)
        {
            string query = strCount;
            int Count = -1;
            try
            {
                if (this.OpenConnection() == true)
                {
                    OleDbCommand cmd = new OleDbCommand(query, connection);
                    Count = int.Parse(cmd.ExecuteScalar().ToString());
                    this.CloseConnection();
                }
            }
            catch (OleDbException ex)
            {
                MessageBox.Show("數據庫操作失敗 ErrorCode: " + (ex.ErrorCode).ToString());
            }
            return Count;
        }

        //執行求和語句
        public double Sum(string strSum)
        {
            string query = strSum;
            double Sum = 0.0;
            try
            {
                if (this.OpenConnection() == true)
                {
                    OleDbCommand cmd = new OleDbCommand(query, connection);
                    Sum = double.Parse(cmd.ExecuteScalar().ToString());
                    this.CloseConnection();
                }
            }
            catch (OleDbException ex)
            {
                MessageBox.Show("數據庫操作失敗 ErrorCode: " + (ex.ErrorCode).ToString());
            }
            return Sum;
        }

        //transaction process
        public bool RunTransaction(string[] strQuerys)
        {
            if (strQuerys.Length > 0)
            {
                try
                {
                    OleDbCommand cmd = new OleDbCommand();
                    cmd.Connection = this.connection;
                    OleDbTransaction transaction = null;
                    if (this.OpenConnection() == true)
                    {
                        transaction = connection.BeginTransaction();
                        cmd.Transaction = transaction;
                        for (int i = 0; i < strQuerys.Length; i++)
                        {
                            cmd.CommandText = strQuerys[i];
                            cmd.ExecuteNonQuery();
                        }
                        transaction.Commit();
                        this.CloseConnection();
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }
                catch (OleDbException ex)
                {
                    MessageBox.Show("數據庫操作失敗 ErrorCode: " + (ex.ErrorCode).ToString());
                    return false;
                }
            }
            else
            {
                return false;
            }
        }
///////////////////////////////////////
    }
}