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      強大的數(shù)據(jù)庫操作類DBHelper
      
                    
                    
                    
                    
      
                         黃金屋1
                        
                        
                        2017-09-11
                        
                            
                        
                    
      
                    
      
                        
                        
      
                    
      
                    
                    
      
                        
      
                            
                        
      
                        
      
                            
                                
      
                                    
                                        
      

                                        
                                        

                                        
       本示例代碼的關(guān)鍵是利用.net庫自帶的DbProviderFactory來生產(chǎn)數(shù)據(jù)庫操作對象。
      

      
從下圖中，可以看到其的多個核心方法，這些方法將在我們的超級DBHelper中使用。
      

      

      

      

      

      

      

      
仔細研究，你會發(fā)現(xiàn)每個數(shù)據(jù)庫的官方支持dll都有一個Instance對象，這個對象都是繼承了DbProviderFactory了。
      

      
因此利用這點，我們就可以實現(xiàn)兼容多種數(shù)據(jù)的超級DBHelper了。
      

      
以下為示例代碼,僅供參考學(xué)習(xí)，代碼只是我的ORM框架中的一個片段（其中暫時支持了SQLSERVER、MYSQL、SQLITE三種數(shù)據(jù)庫，LoadDbProviderFactory方法是將封裝在dll中的數(shù)據(jù)庫操作dll反射加載實例化的方法。）：
      

      

      

      

      

      
[csharp] view
 plain copy

 
      

      

        

      1. 
/// <summary>  
      2. 
    /// 超級數(shù)據(jù)庫操作類  
      3. 
    /// <para>2015年12月21日</para>  
      4. 
    /// <para>v1.0</para>  
      5. 
    /// <para>葉琪</para>  
      6. 
    /// </summary>  
      7. 
    public class DBHelper  
      8. 
    {  
      9. 
        #region 屬性  
      10. 
        private DbProviderFactory _DbFactory;  
      11. 
        private DBConfig mDBConfig;  
      12. 
          
      13. 
        /// <summary>  
      14. 
        /// 數(shù)據(jù)庫連接配置  
      15. 
        /// </summary>  
      16. 
        public DBConfig DBConfig  
      17. 
        {  
      18. 
            get { return mDBConfig; }  
      19. 
        }  
      20. 
  
      21. 
        /// <summary>  
      22. 
        /// 表示一組方法，這些方法用于創(chuàng)建提供程序?qū)?shù)據(jù)源類的實現(xiàn)的實例。  
      23. 
        /// </summary>  
      24. 
        public DbProviderFactory DbFactory  
      25. 
        {  
      26. 
            get { return _DbFactory; }  
      27. 
            set { _DbFactory = value; }  
      28. 
        }  
      29. 
        #endregion  
      30. 
 
      31. 
        #region 構(gòu)造函數(shù)  
      32. 
        public DBHelper(DBConfig aORMConfig)  
      33. 
        {  
      34. 
            mDBConfig = aORMConfig;  
      35. 
            switch (mDBConfig.DBType)  
      36. 
            {  
      37. 
                case ORMType.DBTypes.SQLSERVER:  
      38. 
                    _DbFactory = System.Data.SqlClient.SqlClientFactory.Instance;  
      39. 
                    break;  
      40. 
                case ORMType.DBTypes.MYSQL:  
      41. 
                    LoadDbProviderFactory("MySql.Data.dll", "MySql.Data.MySqlClient.MySqlClientFactory");  
      42. 
                    break;  
      43. 
                case ORMType.DBTypes.SQLITE:  
      44. 
                    LoadDbProviderFactory("System.Data.SQLite.dll", "System.Data.SQLite.SQLiteFactory");  
      45. 
                    break;  
      46. 
            }  
      47. 
        }  
      48. 
  
      49. 
        /// <summary>  
      50. 
        /// 動態(tài)載入數(shù)據(jù)庫封裝庫  
      51. 
        /// </summary>  
      52. 
        /// <param name="aDLLName">數(shù)據(jù)庫封裝庫文件名稱</param>  
      53. 
        /// <param name="aFactoryName">工廠路徑名稱</param>  
      54. 
        private void LoadDbProviderFactory(string aDLLName, string aFactoryName)  
      55. 
        {  
      56. 
            string dllPath = string.Empty;  
      57. 
            if (System.AppDomain.CurrentDomain.RelativeSearchPath != null)  
      58. 
            {  
      59. 
                dllPath = System.AppDomain.CurrentDomain.RelativeSearchPath+"\\"+ aDLLName;  
      60. 
            }  
      61. 
            else  
      62. 
            {  
      63. 
                dllPath = System.AppDomain.CurrentDomain.BaseDirectory + aDLLName;  
      64. 
            }  
      65. 
            if (!File.Exists(dllPath))  
      66. 
            {//文件不存在，從庫資源中復(fù)制輸出到基目錄下  
      67. 
                FileStream fdllFile = new FileStream(dllPath,FileMode.Create);  
      68. 
                byte[] dllData = null;  
      69. 
                if (aDLLName == "System.Data.SQLite.dll")  
      70. 
                {  
      71. 
                    dllData = YFmk.ORM.Properties.Resources.System_Data_SQLite;  
      72. 
                }  
      73. 
                else if (aDLLName == "MySql.Data.dll")  
      74. 
                {  
      75. 
                    dllData = YFmk.ORM.Properties.Resources.MySql_Data;  
      76. 
                }  
      77. 
                fdllFile.Write(dllData, 0, dllData.Length);  
      78. 
                fdllFile.Close();  
      79. 
            }  
      80. 
            Assembly libAssembly = Assembly.LoadFile(dllPath);  
      81. 
            Type type = libAssembly.GetType(aFactoryName);  
      82. 
            foreach (FieldInfo fi in type.GetFields(BindingFlags.Static | BindingFlags.Public))  
      83. 
            {  
      84. 
                if (fi.Name == "Instance")  
      85. 
                {  
      86. 
                    _DbFactory = fi.GetValue(null) as DbProviderFactory;  
      87. 
                    return;  
      88. 
                }  
      89. 
            }  
      90. 
        }  
      91. 
        #endregion  
      92. 
 
      93. 
        #region 數(shù)據(jù)庫操作  
      94. 
        /// <summary>  
      95. 
        /// 執(zhí)行一條計算查詢結(jié)果語句，返回查詢結(jié)果  
      96. 
        /// </summary>  
      97. 
        /// <param name="aSQLWithParameter">SQL語句及參數(shù)</param>  
      98. 
        /// <returns>查詢結(jié)果（object）</returns>  
      99. 
        public object GetSingle(SQLWithParameter aSQLWithParameter)  
      100. 
        {  
      101. 
            using (DbConnection conn = _DbFactory.CreateConnection())  
      102. 
            {  
      103. 
                conn.ConnectionString = mDBConfig.ConnString;  
      104. 
                using (DbCommand cmd = _DbFactory.CreateCommand())  
      105. 
                {  
      106. 
                    PrepareCommand(cmd, conn, aSQLWithParameter.SQL.ToString(), aSQLWithParameter.Parameters);  
      107. 
                    object obj = cmd.ExecuteScalar();  
      108. 
                    cmd.Parameters.Clear();  
      109. 
                    if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))  
      110. 
                    {  
      111. 
                        return null;  
      112. 
                    }  
      113. 
                    else  
      114. 
                    {  
      115. 
                        return obj;  
      116. 
                    }  
      117. 
                }  
      118. 
            }  
      119. 
        }  
      120. 
  
      121. 
        /// <summary>  
      122. 
        /// 執(zhí)行SQL語句，返回影響的記錄數(shù)  
      123. 
        /// </summary>  
      124. 
        /// <param name="aSQL">SQL語句</param>  
      125. 
        /// <returns>影響的記錄數(shù)</returns>  
      126. 
        public int ExecuteSql(string aSQL)  
      127. 
        {  
      128. 
            using (DbConnection conn = _DbFactory.CreateConnection())  
      129. 
            {  
      130. 
                conn.ConnectionString = mDBConfig.ConnString;  
      131. 
                using (DbCommand cmd = _DbFactory.CreateCommand())  
      132. 
                {  
      133. 
                    PrepareCommand(cmd, conn, aSQL);  
      134. 
                    int rows = cmd.ExecuteNonQuery();  
      135. 
                    cmd.Parameters.Clear();  
      136. 
                    return rows;  
      137. 
                }  
      138. 
            }  
      139. 
        }  
      140. 
  
      141. 
        /// <summary>  
      142. 
        /// 執(zhí)行SQL語句，返回影響的記錄數(shù)  
      143. 
        /// </summary>  
      144. 
        /// <param name="aSQLWithParameter">SQL語句及參數(shù)</param>  
      145. 
        /// <returns></returns>  
      146. 
        public int ExecuteSql(SQLWithParameter aSQLWithParameter)  
      147. 
        {  
      148. 
            using (DbConnection conn = _DbFactory.CreateConnection())  
      149. 
            {  
      150. 
                conn.ConnectionString = mDBConfig.ConnString;  
      151. 
                using (DbCommand cmd = _DbFactory.CreateCommand())  
      152. 
                {  
      153. 
                    PrepareCommand(cmd, conn, aSQLWithParameter.SQL.ToString(), aSQLWithParameter.Parameters);  
      154. 
                    int rows = cmd.ExecuteNonQuery();  
      155. 
                    cmd.Parameters.Clear();  
      156. 
                    return rows;  
      157. 
                }  
      158. 
            }  
      159. 
        }  
      160. 
  
      161. 
        /// <summary>  
      162. 
        /// 執(zhí)行多條SQL語句，實現(xiàn)數(shù)據(jù)庫事務(wù)。  
      163. 
        /// </summary>  
      164. 
        /// <param name="aSQLWithParameterList">參數(shù)化的SQL語句結(jié)構(gòu)體對象集合</param>          
      165. 
        public string ExecuteSqlTran(List<SQLWithParameter> aSQLWithParameterList)  
      166. 
        {  
      167. 
            using (DbConnection conn = _DbFactory.CreateConnection())  
      168. 
            {  
      169. 
                conn.ConnectionString = mDBConfig.ConnString;  
      170. 
                conn.Open();  
      171. 
                DbTransaction fSqlTransaction = conn.BeginTransaction();  
      172. 
                try  
      173. 
                {  
      174. 
                    List<DbCommand> fTranCmdList = new List<DbCommand>();  
      175. 
                    //創(chuàng)建新的CMD  
      176. 
                    DbCommand fFirstCMD = _DbFactory.CreateCommand();  
      177. 
                    fFirstCMD.Connection = conn;  
      178. 
                    fFirstCMD.Transaction = fSqlTransaction;  
      179. 
                    fTranCmdList.Add(fFirstCMD);  
      180. 
                    int NowCmdIndex = 0;//當(dāng)前執(zhí)行的CMD索引值  
      181. 
                    int ExecuteCount = 0;//已經(jīng)執(zhí)行的CMD次數(shù)  
      182. 
                    StringBuilder fSQL = new StringBuilder();  
      183. 
                    foreach (SQLWithParameter fSQLWithParameter in aSQLWithParameterList)  
      184. 
                    {  
      185. 
                        fSQL.Append(fSQLWithParameter.SQL.ToString() + ";");  
      186. 
                        fTranCmdList[NowCmdIndex].Parameters.AddRange(fSQLWithParameter.Parameters.ToArray());  
      187. 
                        if (fTranCmdList[NowCmdIndex].Parameters.Count > 2000)  
      188. 
                        { //參數(shù)達到2000個，執(zhí)行一次CMD  
      189. 
                            fTranCmdList[NowCmdIndex].CommandText = fSQL.ToString();  
      190. 
                            fTranCmdList[NowCmdIndex].ExecuteNonQuery();  
      191. 
                            DbCommand fNewCMD = _DbFactory.CreateCommand();  
      192. 
                            fNewCMD.Connection = conn;  
      193. 
                            fNewCMD.Transaction = fSqlTransaction;  
      194. 
                            fTranCmdList.Add(fNewCMD);  
      195. 
                            NowCmdIndex++;  
      196. 
                            ExecuteCount++;  
      197. 
                            fSQL.Clear();//清空SQL  
      198. 
                        }  
      199. 
                    }  
      200. 
                    if (ExecuteCount < fTranCmdList.Count)  
      201. 
                    {//已執(zhí)行CMD次數(shù)小于總CMD數(shù)，執(zhí)行最后一條CMD  
      202. 
                        fTranCmdList[fTranCmdList.Count - 1].CommandText = fSQL.ToString();  
      203. 
                        fTranCmdList[fTranCmdList.Count - 1].ExecuteNonQuery();  
      204. 
                    }  
      205. 
                    fSqlTransaction.Commit();  
      206. 
                    return null;  
      207. 
                }  
      208. 
                catch (Exception ex)  
      209. 
                {  
      210. 
                    fSqlTransaction.Rollback();  
      211. 
                    StringBuilder fSQL = new StringBuilder();  
      212. 
                    foreach (SQLWithParameter fSQLWithParameter in aSQLWithParameterList)  
      213. 
                    {  
      214. 
                        fSQL.Append(fSQLWithParameter.SQL.ToString() + ";");  
      215. 
                    }  
      216. 
                    YFmk.Lib.LocalLog.WriteByDate(fSQL.ToString()+" 錯誤："+ex.Message, "ORM");  
      217. 
                    return ex.Message;  
      218. 
                }  
      219. 
            }  
      220. 
        }  
      221. 
  
      222. 
        /// <summary>  
      223. 
        /// 執(zhí)行查詢語句，返回DataSet  
      224. 
        /// </summary>  
      225. 
        /// <param name="SQLString">查詢語句</param>  
      226. 
        /// <returns>DataSet</returns>  
      227. 
        public DataSet Query(string SQLString)  
      228. 
        {  
      229. 
            using (DbConnection conn = _DbFactory.CreateConnection())  
      230. 
            {  
      231. 
                conn.ConnectionString = mDBConfig.ConnString;  
      232. 
                using (DbCommand cmd = _DbFactory.CreateCommand())  
      233. 
                {  
      234. 
                    PrepareCommand(cmd, conn, SQLString);  
      235. 
                    using (DbDataAdapter da = _DbFactory.CreateDataAdapter())  
      236. 
                    {  
      237. 
                        da.SelectCommand = cmd;  
      238. 
                        DataSet ds = new DataSet();  
      239. 
                        try  
      240. 
                        {  
      241. 
                            da.Fill(ds, "ds");  
      242. 
                            cmd.Parameters.Clear();  
      243. 
                        }  
      244. 
                        catch (Exception ex)  
      245. 
                        {  
      246. 
                              
      247. 
                        }  
      248. 
                        return ds;  
      249. 
                    }  
      250. 
                }  
      251. 
            }  
      252. 
        }  
      253. 
  
      254. 
        /// <summary>  
      255. 
        /// 執(zhí)行查詢語句，返回DataSet  
      256. 
        /// </summary>  
      257. 
        /// <param name="aSQLWithParameter">查詢語句</param>  
      258. 
        /// <returns>DataSet</returns>  
      259. 
        public DataSet Query(SQLWithParameter aSQLWithParameter)  
      260. 
        {  
      261. 
            using (DbConnection conn = _DbFactory.CreateConnection())  
      262. 
            {  
      263. 
                conn.ConnectionString = mDBConfig.ConnString;  
      264. 
                using (DbCommand cmd = _DbFactory.CreateCommand())  
      265. 
                {  
      266. 
                    PrepareCommand(cmd, conn, aSQLWithParameter.SQL.ToString(), aSQLWithParameter.Parameters);  
      267. 
                    using (DbDataAdapter da = _DbFactory.CreateDataAdapter())  
      268. 
                    {  
      269. 
                        da.SelectCommand = cmd;  
      270. 
                        DataSet ds = new DataSet();  
      271. 
                        da.Fill(ds, "ds");  
      272. 
                        cmd.Parameters.Clear();  
      273. 
                        return ds;  
      274. 
                    }  
      275. 
                }  
      276. 
            }  
      277. 
        }  
      278. 
        #endregion  
      279. 
 
      280. 
        #region 私有函數(shù)  
      281. 
        private void PrepareCommand(DbCommand cmd, DbConnection conn, string cmdText)  
      282. 
        {  
      283. 
            if (conn.State != ConnectionState.Open)  
      284. 
                conn.Open();  
      285. 
            cmd.Connection = conn;  
      286. 
            cmd.CommandText = cmdText;  
      287. 
        }  
      288. 
  
      289. 
        private void PrepareCommand(DbCommand cmd, DbConnection conn, string cmdText, List<DbParameter> cmdParms)  
      290. 
        {  
      291. 
            if (conn.State != ConnectionState.Open)  
      292. 
                conn.Open();  
      293. 
            cmd.Connection = conn;  
      294. 
            cmd.CommandText = cmdText;  
      295. 
            if (cmdParms != null && cmdParms.Count>0)  
      296. 
            {  
      297. 
                cmd.Parameters.AddRange(cmdParms.ToArray());  
      298. 
            }  
      299. 
        }  
      300. 
        #endregion  
      

      
                                          		
                                
      
                                  
                        
      
                    
      



                
      
                
      
                    
                    
                        
      
                            
                                
        
                                    		
                        
        
                            
                
        
                
        
                
                
                
        
                
        


                

                
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