c# DbHelper的封装

基于ADO.NET框架，封装了适用于多个关系型数据库的DbHelper。通过简洁明了的代码，实现了对各种数据库的高效操作。

public class DbHelper{private readonly DataBase _dataBase;public DbHelper(DataBase dataBase){_dataBase = dataBase;}public DataBase GetDataBase(){return _dataBase;}public DbConnection GetDbConnection(){var conn = _dataBase.CreationConnection();if (conn.State == ConnectionState.Closed){conn.Open();}return conn;}/// <summary>/// 执行语句/// </summary>/// <param name="sql">sql语句</param>/// <param name="cmdParms">参数</param>/// <returns></returns>public int Execute(string sql, params DbParameter[] cmdParms){using (DbConnection connection = GetDbConnection()){using (DbCommand cmd = connection.CreateCommand()){try{PrepareCommand(cmd, connection, null, sql, cmdParms);int rows = cmd.ExecuteNonQuery();cmd.Parameters.Clear();return rows;}catch (DbException e){throw e;}}}}/// <summary>/// 批量查询/// </summary>/// <param name="sql">sql语句</param>/// <param name="cmdParms">参数</param>/// <returns></returns>public DataSet Query(string sql, params DbParameter[] cmdParms){using (DbConnection connection = GetDbConnection()){DataSet ds = new DataSet();try{DbProviderFactory factory = DbProviderFactories.GetFactory(connection);DbCommand command = factory.CreateCommand();PrepareCommand(command, connection, null, sql, cmdParms);DbDataAdapter adapter = factory.CreateDataAdapter();adapter.SelectCommand = command;adapter.Fill(ds, "ds");adapter.Dispose();command.Dispose();}catch (DbException ex){throw ex;}return ds;}}/// <summary>/// 批量查询/// </summary>/// <typeparam name="T"></typeparam>/// <param name="sql">sql语句</param>/// <param name="reader">数据读取器</param>/// <param name="cmdParms">参数</param>/// <returns></returns>/// <exception cref="Exception"></exception>public List<T> Query<T>(string sql, Func<IDataReader, T> reader, params DbParameter[] cmdParms){if (reader == null)throw new Exception("数据读取器是空的!");List<T> list = new List<T>();using (DbConnection connection = GetDbConnection()){using (DbCommand cmd = connection.CreateCommand()){try{PrepareCommand(cmd, connection, null, sql, cmdParms);DbDataReader myReader = cmd.ExecuteReader();cmd.Parameters.Clear();while (myReader.Read()){list.Add(reader(myReader));}myReader.Close();}catch (DbException e){throw e;}}}return list;}/// <summary>/// 单个查询/// </summary>/// <typeparam name="T"></typeparam>/// <param name="sql">sql语句</param>/// <param name="reader">数据读取器</param>/// <param name="cmdParms">参数</param>/// <returns></returns>/// <exception cref="Exception"></exception>public T QueryFirstOrDefault<T>(string sql, Func<IDataReader, T> reader, params DbParameter[] cmdParms){if (reader == null){throw new Exception("数据读取器是空的!");}var model = default(T);using (DbConnection connection = GetDbConnection()){using (DbCommand cmd = connection.CreateCommand()){try{PrepareCommand(cmd, connection, null, sql, cmdParms);DbDataReader myReader = cmd.ExecuteReader();cmd.Parameters.Clear();if (myReader.Read())model = reader(myReader);myReader.Close();}catch (DbException e){throw e;}}}return model;}/// <summary>/// 执行存储过程/// </summary>/// <param name="storedProcName">存储过程名</param>/// <param name="parameters">存储过程参数</param>/// <returns></returns>public DataSet RunProcedure(string storedProcName, DbParameter[] parameters){using (DbConnection connection = GetDbConnection()){DataSet dataSet = new DataSet();connection.Open();DbDataAdapter sqlDA = DbProviderFactories.GetFactory(connection).CreateDataAdapter();sqlDA.SelectCommand = BuildQueryCommand(connection, storedProcName, parameters);sqlDA.Fill(dataSet, "ds");sqlDA.SelectCommand.Dispose();sqlDA.Dispose();return dataSet;}}/// <summary>/// 执行存储过程，返回SqlDataReader ( 注意：调用该方法后，一定要对SqlDataReader进行Close )/// </summary>/// <param name="storedProcName">存储过程名</param>/// <param name="parameters">存储过程参数</param>/// <returns>SqlDataReader</returns>public DbDataReader RunProcedureToReader(string storedProcName, DbParameter[] parameters){using (DbConnection connection = GetDbConnection()){DbDataReader returnReader;connection.Open();DbCommand command = BuildQueryCommand(connection, storedProcName, parameters);command.CommandType = CommandType.StoredProcedure;returnReader = command.ExecuteReader(CommandBehavior.CloseConnection);command.Dispose();return returnReader;}}/// <summary>/// 执行存储过程/// </summary>/// <param name="storedProcName">存储过程名</param>/// <param name="parameters">存储过程参数</param>/// <returns>SqlDataReader</returns>public T RunProcedure<T>(string storedProcName, Func<IDataReader, T> reader, DbParameter[] parameters){if (reader == null){throw new Exception("数据读取器是空的!");}T t = default(T);using (DbConnection connection = GetDbConnection()){DbDataReader returnReader;connection.Open();DbCommand command = BuildQueryCommand(connection, storedProcName, parameters);command.CommandType = CommandType.StoredProcedure;returnReader = command.ExecuteReader(CommandBehavior.CloseConnection);command.Dispose();if (returnReader.Read())t = reader(returnReader);returnReader.Close();}return t;}/// <summary>/// 执行存储过程/// </summary>/// <param name="storedProcName">存储过程名</param>/// <param name="parameters">存储过程参数</param>/// <returns>SqlDataReader</returns>public List<T> RunProcedureToList<T>(string storedProcName, Func<IDataReader, T> reader, DbParameter[] parameters){if (reader == null){throw new Exception("数据读取器是空的!");}List<T> list = new List<T>();using (DbConnection connection = GetDbConnection()){DbDataReader returnReader;connection.Open();DbCommand command = BuildQueryCommand(connection, storedProcName, parameters);command.CommandType = CommandType.StoredProcedure;returnReader = command.ExecuteReader(CommandBehavior.CloseConnection);command.Dispose();while (returnReader.Read())list.Add(reader(returnReader));returnReader.Close();}return list;}/// <summary>/// 返回首行首列/// </summary>/// <param name="sql">sql语句</param>/// <param name="cmdParms">参数</param>/// <returns></returns>public object ExecuteScalar(string sql, params DbParameter[] cmdParms){object result = null;using (DbConnection connection = GetDbConnection()){using (DbCommand cmd = connection.CreateCommand()){try{PrepareCommand(cmd, connection, null, sql, cmdParms);result = cmd.ExecuteScalar();}catch (DbException e){throw e;}}}return result;}/// <summary>/// 分页列表/// </summary>/// <typeparam name="T"></typeparam>/// <param name="tablename">表名(可以自定)</param>/// <param name="page">分页信息</param>/// <param name="reader">读取器</param>/// <param name="where">条件</param>/// <param name="field">字段</param>/// <param name="order">排序</param>public List<T> QueryWithPage<T>(string tablename, PageInfo page, Func<IDataReader, T> reader, string where = "", string field = "*", string order = "", params DbParameter[] cmdParms){long offset = page.Index * page.PageSize;string sql = "SELECT " + field + " FROM " + tablename;sql = ListPageSql(sql, where, order);sql = sql + " " + Limit(offset, page.PageSize);string sql2 = "SELECT COUNT(0) FROM " + tablename;sql2 = ListPageSql(sql2, where, "");string sql3 = sql + ";" + sql2;List<T> list = new List<T>();using (DbConnection conn = GetDbConnection()){using (DbCommand cmd = conn.CreateCommand()){try{PrepareCommand(cmd, conn, null, sql3, cmdParms);DbDataReader myReader = cmd.ExecuteReader();cmd.Parameters.Clear();while (myReader.Read()){list.Add(reader(myReader));}if (myReader.NextResult() && myReader.Read())page.Count = myReader.GetInt64Ex(0);myReader.Close();}catch (MySqlException e){throw new Exception(e.Message);}}}return list;}/// <summary>/// 组装分页sql/// </summary>/// <param name="sql">基础sql</param>/// <param name="where">条件</param>/// <param name="order">排序</param>/// <returns></returns>private string ListPageSql(string sql, string where, string order){if (!string.IsNullOrEmpty(where)){sql = sql + " WHERE " + where;}if (!string.IsNullOrEmpty(order)){sql = sql + " " + order;}return sql;}/// <summary>/// 分页/// </summary>/// <param name="offset">偏移</param>/// <param name="size">每页显示数据尺寸</param>/// <returns></returns>/// <exception cref="Exception"></exception>public string Limit(long offset, long size){if (offset == -1){if (_dataBase.DbType != DbBaseType.SqlServer){return "LIMIT " + size;}}else{if (_dataBase.DbType == DbBaseType.MySql){return string.Format("LIMIT {0},{1}", offset, size);}if (_dataBase.DbType == DbBaseType.PostgreSql || _dataBase.DbType == DbBaseType.Sqlite){return string.Format(" LIMIT {0} OFFSET {1}", size, offset);}}throw new Exception("暂时不支持其它分页语法");}public DbParameter CreateDbParameter(string parameterName, DbType dbType, object value){using(DbConnection connection = GetDbConnection()){DbParameter dbParameter = DbProviderFactories.GetFactory(connection).CreateParameter();dbParameter.ParameterName = parameterName;dbParameter.DbType = dbType;dbParameter.Value = value;return dbParameter;}}protected void PrepareCommand(DbCommand cmd, DbConnection conn, DbTransaction trans, string cmdText, DbParameter[] cmdParms){cmd.Connection = conn;cmd.CommandText = cmdText;if (trans != null)cmd.Transaction = trans;cmd.CommandType = CommandType.Text;SetParameters(cmd, cmdParms);}private DbCommand BuildQueryCommand(DbConnection connection, string storedProcName, DbParameter[] parameters){DbCommand command = connection.CreateCommand();command.CommandText = storedProcName;command.CommandType = CommandType.StoredProcedure;SetParameters(command, parameters);return command;}private void SetParameters(DbCommand command, DbParameter[] cmdParms){if (cmdParms != null){foreach (var parameter in cmdParms){if ((parameter.Direction == ParameterDirection.InputOutput||parameter.Direction == ParameterDirection.Input)&&(parameter.Value == null)){parameter.Value = DBNull.Value;}command.Parameters.Add(parameter);}}}}