新手请教:数据库连接必须每一个FORM都有一个吗?

[菩提998866]

刚学习C#,不明白的问题有不少,在这里想向各位高手请教一下:在一个系统中,如果要用到多个窗体,必须在每个窗体中都单独地建立连接数据库吗,有办法公用一个连接,在各个窗体中都可以用吗?

[xiaoyue520]

接分中.........


一个就可以搞定

[chenyijiu]

[Quote=引用 3 楼 zihua 的回复:]
将连接放在一个类库中,用时是新生成实例吧,是不是相当于两个连接?
[/Quote]
你可以把类写成静态的

[mywisest]

如果连接一个数据库,那就用一个好了.
如果连接多个数据库,那就得用多个.

[wjp_116]

[Quote=引用 5 楼 chenyijiu 的回复:]
引用 3 楼 zihua 的回复:
将连接放在一个类库中,用时是新生成实例吧,是不是相当于两个连接?

你可以把类写成静态的
[/Quote]
同意

[luluyy]

private sealed class sqlheaper()
{
		#region ExecuteNonQuery



		public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText)
		{
			// Pass through the call providing null for the set of SqlParameters
			return ExecuteNonQuery(connectionString, commandType, commandText, (SqlParameter[])null);
		}

		public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
		{
			if( connectionString == null || connectionString.Length == 0 ) throw new ArgumentNullException( "connectionString" );

			// Create & open a SqlConnection, and dispose of it after we are done
			using (SqlConnection connection = new SqlConnection(connectionString))
			{
				connection.Open();

				// Call the overload that takes a connection in place of the connection string
				return ExecuteNonQuery(connection, commandType, commandText, commandParameters);
			}
		}
		public static int ExecuteNonQuery(string connectionString, string spName, params object[] parameterValues)
		{
			if( connectionString == null || connectionString.Length == 0 ) throw new ArgumentNullException( "connectionString" );
			if( spName == null || spName.Length == 0 ) throw new ArgumentNullException( "spName" );

			// If we receive parameter values, we need to figure out where they go
			if ((parameterValues != null) && (parameterValues.Length > 0)) 
			{
				// Pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				SqlParameter[] commandParameters = SqlHelperParameterCache.GetSpParameterSet(connectionString, spName);

				// Assign the provided values to these parameters based on parameter order
				AssignParameterValues(commandParameters, parameterValues);

				// Call the overload that takes an array of SqlParameters
				return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName, commandParameters);
			}
			else 
			{
				// Otherwise we can just call the SP without params
				return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName);
			}
		}

				public static int ExecuteNonQuery(SqlConnection connection, CommandType commandType, string commandText)
		{
			// Pass through the call providing null for the set of SqlParameters
			return ExecuteNonQuery(connection, commandType, commandText, (SqlParameter[])null);
		}
		public static int ExecuteNonQuery(SqlConnection connection, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
		{	
			if( connection == null ) throw new ArgumentNullException( "connection" );

			// Create a command and prepare it for execution
			SqlCommand cmd = new SqlCommand();
			bool mustCloseConnection = false;
			PrepareCommand(cmd, connection, (SqlTransaction)null, commandType, commandText, commandParameters, out mustCloseConnection );
    		
			// Finally, execute the command
			int retval = cmd.ExecuteNonQuery();
    		
			// Detach the SqlParameters from the command object, so they can be used again
			cmd.Parameters.Clear();
			if( mustCloseConnection )
				connection.Close();
			return retval;
		}
		public static int ExecuteNonQuery(SqlConnection connection, string spName, params object[] parameterValues)
		{
			if( connection == null ) throw new ArgumentNullException( "connection" );
			if( spName == null || spName.Length == 0 ) throw new ArgumentNullException( "spName" );

			// If we receive parameter values, we need to figure out where they go
			if ((parameterValues != null) && (parameterValues.Length > 0)) 
			{
				// Pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				SqlParameter[] commandParameters = SqlHelperParameterCache.GetSpParameterSet(connection, spName);

				// Assign the provided values to these parameters based on parameter order
				AssignParameterValues(commandParameters, parameterValues);

				// Call the overload that takes an array of SqlParameters
				return ExecuteNonQuery(connection, CommandType.StoredProcedure, spName, commandParameters);
			}
			else 
			{
				// Otherwise we can just call the SP without params
				return ExecuteNonQuery(connection, CommandType.StoredProcedure, spName);
			}
		}

				public static int ExecuteNonQuery(SqlTransaction transaction, CommandType commandType, string commandText)
		{
			// Pass through the call providing null for the set of SqlParameters
			return ExecuteNonQuery(transaction, commandType, commandText, (SqlParameter[])null);
		}

				public static int ExecuteNonQuery(SqlTransaction transaction, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
		{
			if( transaction == null ) throw new ArgumentNullException( "transaction" );
			if( transaction != null && transaction.Connection == null ) throw new ArgumentException( "The transaction was rollbacked or commited, please provide an open transaction.", "transaction" );

			// Create a command and prepare it for execution
			SqlCommand cmd = new SqlCommand();
			bool mustCloseConnection = false;
			PrepareCommand(cmd, transaction.Connection, transaction, commandType, commandText, commandParameters, out mustCloseConnection );
    			
			// Finally, execute the command
			int retval = cmd.ExecuteNonQuery();
    			
			// Detach the SqlParameters from the command object, so they can be used again
			cmd.Parameters.Clear();
			return retval;
		}

				public static int ExecuteNonQuery(SqlTransaction transaction, string spName, params object[] parameterValues)
		{
			if( transaction == null ) throw new ArgumentNullException( "transaction" );
			if( transaction != null && transaction.Connection == null ) throw new ArgumentException( "The transaction was rollbacked or commited, please provide an open transaction.", "transaction" );
			if( spName == null || spName.Length == 0 ) throw new ArgumentNullException( "spName" );

			// If we receive parameter values, we need to figure out where they go
			if ((parameterValues != null) && (parameterValues.Length > 0)) 
			{
				// Pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				SqlParameter[] commandParameters = SqlHelperParameterCache.GetSpParameterSet(transaction.Connection, spName);

				// Assign the provided values to these parameters based on parameter order
				AssignParameterValues(commandParameters, parameterValues);

				// Call the overload that takes an array of SqlParameters
				return ExecuteNonQuery(transaction, CommandType.StoredProcedure, spName, commandParameters);
			}
			else 
			{
				// Otherwise we can just call the SP without params
				return ExecuteNonQuery(transaction, CommandType.StoredProcedure, spName);
			}
		}

		#endregion ExecuteNonQuery
}

[luluyy]

把这个写到类里` 变量你要自己定义在用的时候往里面传就行了~~ 不能每个窗体中都写`这样程序的灵活性太差` 如果我不在你的机器上运行了我拿到别的机器上去就不行了`因为连接字符串是不一样的` 再有1`如果程序要改动的话要是写到程序窗体下也会很累~ 写到累里只需要改动类就行了`程序的结构也清晰

[菩提998866]

朋友们:把类写成静态的的意思是什么呢?引用时可以用吗?

[菩提998866]

感谢8楼的朋友!谢谢,我要好好学习研究一下!

[Magicwords]

建议系统的学习一下

[fuda_1985]

看看sqlhelp比较好。7－

[qq283617300]

一个就可以了。看来真的是初学啊。你还是多找写初学者书看看。加油支持爱学习的人

[孤剑]

系统可以建立 数据连接池，
建议系统的学习，不要只停留在理论的基础上。

[fengyecsdn]

如果是WINFORM环境

你完全可以使整个程序只使用一个后台数据库连接。无论是长连或是短连都可以。
作一个公共类，接受请求返回结果。其实没什么复杂的。

但是不建议吧数据库访问“直接”作成静态类。应该是有初始化有释放（实现IDISPOSE，实现DISPOSE方法）而且最好能可靠的释放，是个好风格。 然后在外边再作一层类，可以是静态的类或者方法。这样会有良好的使用习惯。

要是WEB的化，使用一个数据库连接就比较困难而且有危险了。还是各司其职的好，其他理论同上。

[letisgoto]

单独建个类处理连接，无论几个窗体，同调这个连接方法。。。。。。。。。。

[beijingbeerman]

可以单独写一个数据库连接的类，每个form需要链接数据库时可以定义一个实例就可以了。

[zt_100094]

单写一个连接类就可以了，要用的时就调就是了

[随烟而逝]

我也在学习中……

我觉得有些实例的书本基本上有说
你可以看看

[sxmonsy]

写一个DBConnection.cs的类.把连接写在里面.别的地方用的话就来这调.
例如:public static ConnectionStr="...连接字符串";
调用: SqlConnection myConnection = new SqlConnection(DBConnection.ConnectionStr);

[GhostAdai]

路过接分。

[plby]

回复看看