SQLite——簡單的數據庫訪問幫助類

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SQLite;
using System.Threading;
using System.Configuration;

namespace Chn.gzGISer.DataBase.SQLite
{
    /// <summary>
    /// SQL數據庫幫助類
    /// 使用時請設置SQL數據庫的物理路徑 屬性 DbPath
    /// </summary>
    public class SQLiteDataBase : IDataBase<SQLiteDataBase>
    {
        private SQLiteConnection _connection;
        /// <summary>
        /// 構造函數
        /// </summary>
        public SQLiteDataBase()
        {

        }
        /// <summary>
        /// 構造函數
        /// </summary>
        /// <param name="connectionString">連接字符串</param>
        public SQLiteDataBase(string connectionString)
        {
            _connection = new SQLiteConnection(connectionString);
        }
        /// <summary>
        /// 從配置文件中初始化連接字段
        /// </summary>
        /// <param name="connectionStringName">數據庫連接配置文件（.config）中的數據庫連接字段的標籤名</param>
        public void InitSQLiteConnectionFromConfig(string connectionStringName)
        {
            string connectionString = ConfigurationManager.ConnectionStrings[connectionStringName].ConnectionString;
            _connection = new SQLiteConnection(connectionString);
        }
        /// <summary>
        /// 打開Connection連接
        /// </summary>
        public void EnsureConnectionOpen()
        {
            var retries = 3;
            if (_connection.State == ConnectionState.Open)
            {
                return;
            }
            else
            {
                while (retries >= 0 && _connection.State != ConnectionState.Open)
                {
                    _connection.Open();
                    retries--;
                    Thread.Sleep(30);
                }
            }
        }
        /// <summary>
        /// 關閉Connection連接
        /// </summary>
        public void EnsureConnectionClose()
        {
            if (_connection.State == ConnectionState.Open)
            {
                _connection.Close();
            }
        }
        /// <summary>
        /// 釋放Connection連接
        /// </summary>
        public void Dispose()
        {
            if (_connection != null)
            {
                _connection.Dispose();
                _connection = null;
            }
        }

        /// <summary>
        /// 執行查詢 SQL 語句並返回一個表的數據副本
        /// </summary>
        /// <param name="commandText">SQL 語句</param>
        /// <param name="parameters">SQL 語句參數列表</param>
        /// <returns></returns>
        public DataTable ExecuteQuery(string commandText, Dictionary<string, object> parameters)
        {
            if (string.IsNullOrEmpty(commandText))
            {
                throw new Exception("查詢條件爲空");
            }

            DataTable result = null;
            try
            {
                EnsureConnectionOpen();
                SQLiteCommand command = CreatCommand(commandText, parameters);
                using (SQLiteDataAdapter dataAdapter = new SQLiteDataAdapter(command))
                {
                    dataAdapter.Fill(result);
                }                   
            }
            catch (Exception)
            {

                throw;
            }
            finally
            {
                EnsureConnectionClose();
            }
            return result;
        }
        /// <summary>
        /// 執行非查詢 SQLiet 語句
        /// </summary>
        /// <param name="commandText">SQLiet 語句</param>
        /// <param name="parameters">SQLiet 語句參數列表</param>
        /// <returns>受影響的行數</returns>
        public int ExecuteNonQuery(string commandText, Dictionary<string, object> parameters)
        {
            if (string.IsNullOrEmpty(commandText))
            {
                throw new Exception("查詢條件爲空");
            }

            int result = -1;
            try
            {
                EnsureConnectionOpen();
                SQLiteCommand command = CreatCommand(commandText, parameters);
                result = command.ExecuteNonQuery();
            }
            catch (Exception)
            {

                throw;
            }
            finally
            {
                EnsureConnectionClose();
            }
            return result;
        }
        /// <summary>
        /// 執行一個 SQL 語句並返回一個標量
        /// </summary>
        /// <param name="commandText">SQL 語句</param>
        /// <param name="parameters">SQL 語句參數列表</param>
        /// <returns></returns>
        public object ExecuteScalar(string commandText, Dictionary<string, object> parameters)
        {
            if (string.IsNullOrEmpty(commandText))
            {
                throw new Exception("查詢條件爲空");
            }

            object result = null;
            try
            {
                EnsureConnectionOpen();
                SQLiteCommand command = CreatCommand(commandText, parameters);
                result = command.ExecuteScalar();
            }
            catch (Exception)
            {

                throw;
            }
            finally
            {
                EnsureConnectionClose();
            }
            return result;
        }
        private SQLiteCommand CreatCommand(string commadText, Dictionary<string, object> parameters)
        {
            SQLiteCommand command = _connection.CreateCommand();
            command.CommandText = commadText;
            AddParameters(command, parameters);
            return command;
        }
        private void AddParameters(SQLiteCommand command, Dictionary<string, object> parameters)
        {
            if (parameters == null)
            {
                return;
            }

            foreach (KeyValuePair<string, object> param in parameters)
            {
                var parameter = command.CreateParameter();
                parameter.ParameterName = param.Key;
                parameter.Value = param.Value ?? DBNull.Value;
                command.Parameters.Add(parameter);
            }
        }
    }
}