SqlHelper 类

// 一个自用的 SqlHelper 类 利用了刚学习到的 扩展方法 http://technet.microsoft.com/zh-cn/bb383977
    /// <summary>
    /// The SqlHelper class is intended to encapsulate high performance,
    /// scalable best practices for common uses of SqlClient.
    /// </summary>
    public abstract class SqlHelper
    {
        //Database connection strings
        public static readonly string connStr = ConfigurationManager.ConnectionStrings["SQLConnString"].ConnectionString;

        public static int ExecuteNonQuery(string cmdText, params SqlParameter[] cmdParameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                using (SqlCommand cmd = new SqlCommand(cmdText, conn))
                {
                    //if (conn.State != ConnectionState.Open) conn.Open();
                    conn.QuickOpen();
                    cmd.Parameters.Clear();
                    foreach (SqlParameter item in cmdParameters)
                    {
                        cmd.Parameters.Add(item);
                    }
                    return cmd.ExecuteNonQuery();
                }
            }
        }

        /// <summary>
        /// Execute a SqlCommand (that returns no resultset) using an existing SQL Transaction
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:
        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </remarks>
        /// <param name="trans">an existing sql transaction</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or T-SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            return val;
        }

        /// <summary>
        /// 执行一个查询，返回一个object
        /// </summary>
        /// <param name="cmdText">查询文本</param>
        /// <returns>结果</returns>
        public static object ExecuteScalar(string cmdText, params SqlParameter[] cmdParameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                using (SqlCommand cmd = new SqlCommand(cmdText, conn))
                {
                    //if (conn.State != ConnectionState.Open) conn.Open();
                    conn.QuickOpen();
                    cmd.Parameters.Clear();
                    foreach (SqlParameter item in cmdParameters)
                    {
                        cmd.Parameters.Add(item);
                    }

                    return cmd.ExecuteScalar();
                }
            }
        }

        /// <summary>
        /// Execute a SqlCommand (that returns no resultset) using an existing SQL Transaction
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:
        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </remarks>
        /// <param name="trans">an existing sql transaction</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or T-SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static object ExecuteScalar(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
            return cmd.ExecuteScalar();
        }

        /// <summary>
        /// 执行一个查询，返回一个结果集
        /// </summary>
        /// <param name="cmdText">查询文本</param>
        /// <returns>结果集</returns>
        public static DataTable DB_Select(string cmdText, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                using (SqlDataAdapter da = new SqlDataAdapter())
                {
                    da.SelectCommand = BuildQueryCommand(conn, cmdText, CommandType.Text, parameters);
                    DataTable dt = new DataTable();
                    da.Fill(dt);
                    return dt;
                }
            }
        }

        /// <summary>
        /// 执行一个查询，返回一个结果集
        /// </summary>
        /// <param name="cmdText">查询文本</param>
        /// <returns>结果集</returns>
        public static DataTable DB_Select(string cmdText, CommandType type, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                using (SqlDataAdapter da = new SqlDataAdapter())
                {
                    da.SelectCommand = BuildQueryCommand(conn, cmdText, type, parameters);
                    DataTable dt = new DataTable();
                    da.Fill(dt);
                    return dt;
                }
            }
        }

        /// <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>
        /// <param name="tableName">DataSet结果中的表名</param>
        /// <returns>DataSet</returns>
        public static DataTable RunProcedure(string storedProcName, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                conn.QuickOpen();
                DataTable dt = new DataTable();
                //conn.Open();
                SqlDataAdapter sqlDA = new SqlDataAdapter();
                sqlDA.SelectCommand = BuildQueryCommand(conn, storedProcName, parameters);
                sqlDA.Fill(dt);
                return dt;
            }
        }

        /// <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>
        /// <param name="tableName">DataSet结果中的表名</param>
        /// <returns>DataSet</returns>
        public static DataSet RunProcedure(string storedProcName, string tableName, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                conn.QuickOpen();
                DataSet dataSet = new DataSet();
                //conn.Open();
                SqlDataAdapter sqlDA = new SqlDataAdapter();
                sqlDA.SelectCommand = BuildQueryCommand(conn, storedProcName, parameters);
                sqlDA.Fill(dataSet, tableName);
                conn.Close();
                return dataSet;
            }
        }

        /// <summary>
        /// 构建 SqlCommand 对象
        /// </summary>
        /// <param name="connection">数据库连接</param>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <returns>SqlCommand</returns>
        private static SqlCommand BuildQueryCommand(SqlConnection connection, string storedProcName, params SqlParameter[] parameters)
        {
            return BuildQueryCommand(connection, storedProcName, CommandType.StoredProcedure, parameters);
        }

        /// <summary>
        /// 构建 SqlCommand 对象
        /// </summary>
        /// <param name="connection">数据库连接</param>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <returns>SqlCommand</returns>
        private static SqlCommand BuildQueryCommand(SqlConnection connection, string cmdText, CommandType type, params SqlParameter[] parameters)
        {
            SqlCommand command = new SqlCommand(cmdText, connection);
            command.CommandType = type;
            foreach (SqlParameter parameter in parameters)
            {
                if (parameter != null)
                {
                    // 检查未分配值的输出参数,将其分配以DBNull.Value.
                    if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) &&
                        (parameter.Value == null))
                    {
                        parameter.Value = DBNull.Value;
                    }
                    command.Parameters.Add(parameter);
                }
            }

            return command;
        }

        /// <summary>
        /// Prepare a command for execution
        /// </summary>
        /// <param name="cmd">SqlCommand object</param>
        /// <param name="conn">SqlConnection object</param>
        /// <param name="trans">SqlTransaction object</param>
        /// <param name="cmdType">Cmd type e.g. stored procedure or text</param>
        /// <param name="cmdText">Command text, e.g. Select * from Products</param>
        /// <param name="cmdParms">SqlParameters to use in the command</param>
        private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms)
        {
            //if (conn.State != ConnectionState.Open)
            //    conn.Open();
            conn.QuickOpen();
            cmd.Connection = conn;
            cmd.CommandText = cmdText;

            if (trans != null)
                cmd.Transaction = trans;

            cmd.CommandType = cmdType;
            cmd.Parameters.Clear();
            if (cmdParms != null)
            {
                foreach (SqlParameter parameter in cmdParms)
                {
                    if (parameter != null)
                    {
                        // 检查未分配值的输出参数,将其分配以DBNull.Value.
                        if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) && (parameter.Value == null))
                        {
                            parameter.Value = DBNull.Value;
                        }
                        cmd.Parameters.Add(parameter);
                    }
                }
            }

        }
    }

    public static class SqlExtensions
    {
        public static void QuickOpen(this SqlConnection conn)
        {
            int timeout = Generic.ToInt32(ConfigurationManager.AppSettings["TimeOut"]);
            timeout = Math.Max(Math.Min(, timeout), );

            // We'll use a Stopwatch here for simplicity. A comparison to a stored DateTime.Now value could also be used
            Stopwatch sw = new Stopwatch();
            bool connectSuccess = false;

            // Try to open the connection, if anything goes wrong, make sure we set connectSuccess = false
            Thread t = new Thread(delegate()
            {
                try
                {
                    sw.Start();
                    conn.Open();
                    connectSuccess = true;
                }
                catch { }
            });

            // Make sure it's marked as a background thread so it'll get cleaned up automatically
            t.IsBackground = true;
            t.Start();

            // Keep trying to join the thread until we either succeed or the timeout value has been exceeded
            while (timeout > sw.ElapsedMilliseconds)
                if (t.Join())
                    break;

            // If we didn't connect successfully, throw an exception
            if (!connectSuccess)
                throw new Exception("连接超时！\r\n未能连接到数据库！\r\n如有需要，可更改App.config 中的 TimeOut 值");
        }
    }