sqlconnection的close与dispose的区别？

chinaczg 2004-03-11 01:53:43

我想释放一个连接，请问close好还是dispose好？他们的区别是什么？

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Randy002 2004-03-17

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可惜没人回答我的问题~~

con.close() 是关闭连接,实际上是把连接放回ado.net的连接池,并没有真正关闭,所以再次连接时只是把连接从池中拿出来用,速度很快。 con.dispose是用来释放对象的所在内存,相对于new sqlconnection()；只用dispose是不能关闭connection的,两者不是一回事,只用close也不能释放它所占的内存。 conn.dispose() 是销毁连接,彻底关闭。您可能感兴趣的文章:C#基础:Dispose()、Close()、Finalize()的区别详解探讨C#中Dispose方法与Close方法的区别

ADO.NET链接对象（SqlConnection或者OracleConnection）默认情况都开启连接池（平时编程时可能会忽略）。当我们调用Close或者Dispose方法时，实际并不断开连接，而是把连接放回连接池，再次使用时候重连接池中取得空闲资源。因为打开和关闭数据库连接开销比较大，所以连接池对于与数据库链接资源的控制上，加快客户端程序的效率都有很大地帮助。示例中会看到如何控制连接池个数，链接对象关闭连接放回链接池中，有其他连接对象打开连接时重连接池中取得空闲的对应连接。

using System;using System.Collections.Generic;using System.Text;using System.Data;using System.Data.SqlClient; namespace DatabaseOperate{ class SqlOperateInfo { //Suppose your ServerName is "aa",DatabaseName is "bb",UserName is "cc", Password is "dd" private string sqlConnectionCommand = "Data Source=aa;Initial Catalog=bb;User ID=cc;Pwd=dd"; //This table contains two columns:KeywordID int not null,KeywordName varchar(100) not null private string dataTableName = "Basic_Keyword_Test"; private string storedProcedureName = "Sp_InertToBasic_Keyword_Test"; private string sqlSelectCommand = "Select KeywordID, KeywordName From Basic_Keyword_Test"; //sqlUpdateCommand could contain "insert" , "delete" , "update" operate private string sqlUpdateCommand = "Delete From Basic_Keyword_Test Where KeywordID = 1"; public void UseSqlReader() { SqlConnection sqlConnection = new SqlConnection(sqlConnectionCommand); SqlCommand sqlCommand = new SqlCommand(); sqlCommand.CommandType = System.Data.CommandType.Text; sqlCommand.Connection = sqlConnection; sqlCommand.CommandText = sqlSelectCommand; sqlConnection.Open(); SqlDataReader sqlDataReader = sqlCommand.ExecuteReader(); while(sqlDataReader.Read()) { //Get KeywordID and KeywordName , You can do anything you like. Here I just output them. int keywordid = (int)sqlDataReader[0]; //the same as: int keywordid = (int)sqlDataReader["KeywordID"] string keywordName = (string)sqlDataReader[1]; //the same as: string keywordName = (int)sqlDataReader["KeywordName"] Console.WriteLine("KeywordID = " + keywordid + " , KeywordName = " + keywordName); } sqlDataReader.Close(); sqlCommand.Dispose(); sqlConnection.Close(); } public void UseSqlStoredProcedure() { SqlConnection sqlConnection = new SqlConnection(sqlConnectionCommand); SqlCommand sqlCommand = new SqlCommand(); sqlCommand.CommandType = CommandType.StoredProcedure; sqlCommand.Connection = sqlConnection; sqlCommand.CommandText = storedProcedureName; sqlConnection.Open(); sqlCommand.ExecuteNonQuery(); //you can use reader here,too.as long as you modify the sp and let it like select * from .... sqlCommand.Dispose(); sqlConnection.Close(); } public void UseSqlDataSet() { SqlConnection sqlConnection = new SqlConnection(sqlConnectionCommand); SqlCommand sqlCommand = new SqlCommand(); sqlCommand.CommandType = System.Data.CommandType.Text; sqlCommand.Connection = sqlConnection; sqlCommand.CommandText = sqlSelectCommand; sqlConnection.Open(); SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(); sqlDataAdapter.SelectCommand = sqlCommand; DataSet dataSet = new DataSet(); //sqlCommandBuilder is for update the dataset to database SqlCommandBuilder sqlCommandBuilder = new SqlCommandBuilder(sqlDataAdapter); sqlDataAdapter.Fill(dataSet, dataTableName); //Do something to dataset then you can update it to Database.Here I just add a row DataRow row = dataSet.Tables[0].NewRow(); row[0] = 10000; row[1] = "new row"; dataSet.Tables[0].Rows.Add(row); sqlDataAdapter.Update(dataSet, dataTableName); sqlCommand.Dispose(); sqlDataAdapter.Dispose(); sqlConnection.Close(); } }}

C#源代码学生成绩管理系统 #region 执行SQL语句，返回SqlDataReader /// /// 执行SQL语句，返回SqlDataReader /// /// 要执行的SQL语句 /// 返回SqlDataReader，需手工关闭连接 public SqlDataReader GetReader(string sql) { SqlConnection con=new SqlConnection(DataAccess.ConnectionString); SqlCommand cmd=new SqlCommand(sql,con); SqlDataReader dr=null; try { con.Open(); dr=cmd.ExecuteReader(CommandBehavior.CloseConnection); } catch (Exception ex) { dr.Close(); con.Dispose(); cmd.Dispose(); throw new Exception(ex.ToString()); } return dr; } #endregion

using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Data; using System.Data.SqlClient; using System.Configuration; namespace MyOfficeDAL { public static class DBHelper { private static SqlConnection connection; public static SqlConnection Connection { get { string connectionString = ConfigurationManager.ConnectionStrings["MyOfficeConnectionString"].ConnectionString; connection = new SqlConnection(connectionString); if (connection == null) { connection.Open(); } else if (connection.State == System.Data.ConnectionState.Closed) { connection.Open(); } else if (connection.State == System.Data.ConnectionState.Broken) { connection.Close(); connection.Open(); } return connection; } } public static int ExecuteCommand(string safeSql) { SqlCommand cmd = new SqlCommand(safeSql, Connection); int result = cmd.ExecuteNonQuery(); return result; } public static int ExecuteCommand(string sql, params SqlParameter[] values) { SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.AddRange(values); return cmd.ExecuteNonQuery(); } public static string ReturnStringScalar(string safeSql) { SqlCommand cmd = new SqlCommand(safeSql, Connection); try { string result = cmd.ExecuteScalar().ToString(); return result; } catch (Exception ex) { return "0"; } connection.Close(); } public static int GetScalar(string safeSql) { SqlCommand cmd = new SqlCommand(safeSql, Connection); try { int result = Convert.ToInt32(cmd.ExecuteScalar()); return result; } catch (Exception e) { return 0; } connection.Close(); } public static int GetScalar(string sql, params SqlParameter[] values) { SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.AddRange(values); int result = Convert.ToInt32(cmd.ExecuteScalar()); return result; connection.Close(); } public static SqlDataReader GetReader(string safeSql) { SqlCommand cmd = new SqlCommand(safeSql, Connection); SqlDataReader reader = cmd.ExecuteReader(); return reader; reader.Close(); reader.Dispose(); } public static SqlDataReader GetReader(string sql, params SqlParameter[] values) { SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.AddRange(values); SqlDataReader reader = cmd.ExecuteReader(); return reader; reader.Close(); reader.Dispose(); } public static DataTable GetDataSet(string safeSql) { DataSet ds = new DataSet(); SqlCommand cmd = new SqlCommand(safeSql, Connection); SqlDataAdapter da = new SqlDataAdapter(cmd); da.Fill(ds); connection.Close(); connection.Dispose(); return ds.Tables[0]; } public static DataTable GetDataSet(string sql, params SqlParameter[] values) { DataSet ds = new DataSet(); SqlCommand cmd = new SqlCommand(sql, Connection); cmd.Parameters.AddRange(values); SqlDataAdapter da = new SqlDataAdapter(cmd); da.Fill(ds); connection.Close(); connection.Dispose(); return ds.Tables[0]; } } }

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