介绍几种 ADO.net 中的数据库连接方式
在MSDN中，.net的数据库连接字符串都有具体的说明，我这里以代码范例的方式罗列一些，具体的每一项代表的意义可以参看MSDN.
ADO.net 中数据库连接方式(微软提供)
微软提供了以下四种数据库连接方式：
System.Data.OleDb.OleDbConnection
System.Data.SqlClient.SqlConnection
System.Data.Odbc.OdbcConnection
System.Data.OracleClient.OracleConnection
下面我们以范例的方式，来依次说明：
System.Data.SqlClient.SqlConnection
常用的一些连接字符串(C#代码)：
SqlConnection conn
= new SqlConnection( "Server=(local);Integrated Security=SSPI;database=Pubs");
SqlConnection conn
= new SqlConnection("server=(local)\\NetSDK;database=pubs;Integrated Security=SSPI");
SqlConnection conn = new SqlConnection(
"Data Source=localhost;Integrated Security=SSPI;Initial Catalog=Northwind;");
SqlConnection conn = new SqlConnection(
" data source=(local);initial catalog=xr;integrated security=SSPI;
persist security info=False;workstation id=XURUI;packet size=4096; ");
SqlConnection myConn= new
System.Data.SqlClient.SqlConnection("Persist Security Info=False;Integrated
Security=SSPI;database=northwind;server=mysqlServer");
SqlConnection conn = new SqlConnection(
" uid=sa;pwd=passWords;initial catalog=pubs;data source=127.0.0.1;Connect Timeout=900");
更多字符串连接说明请看MSDN：
http://msdn.microsoft.com/library/default.ASP?url=/library/en-us/cpref/Html/frlrfSystemDataSqlClientSqlConnectionClassConnectionStringTopic.asp
System.Data.OleDb.OleDbConnection
常用的一些连接字符串(C#代码)：
OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\MyWeb\81\05\GrocerToGo.mdb");
OleDbConnection conn = new OleDbConnection(
@"Provider=Microsoft.Jet.OLEDB.4.0;Password=;
User ID=Admin;Data Source=grocertogo.mdb;");
OleDbConnection conn = new OleDbConnection(
"Provider=MSDAORA; Data Source=ORACLE8i7;Persist Security Info=False;Integrated Security=yes");
OleDbConnection conn = new OleDbConnection(
"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=c:\bin\LocalAccess40.mdb");
OleDbConnection conn = new OleDbConnection(
"Provider=SQLOLEDB;Data Source=MySQLServer;Integrated Security=SSPI");
更多字符串连接说明请看MSDN：
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfSystemDataOleDbOleDbConnectionClassConnectionStringTopic.asp?frame=true
System.Data.OracleClient.OracleConnection
常用的一些连接字符串(C#代码)：
OracleConnection myConn = new System.Data.OracleClient.OracleConnection(
"Data Source=Oracle8i;Integrated Security=yes");
更多字符串连接说明请看MSDN：
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfSystemDataOracleClientOracleConnectionClassConnectionStringTopic.asp?frame=true
System.Data.Odbc.OdbcConnection
常用的一些连接字符串(C#代码)：
OdbcConnection conn = new OdbcConnection(
"Driver={SQL Server};Server=MyServer;Trusted_Connection=yes;Database=Northwind;");
OdbcConnection conn = new OdbcConnection(
"Driver={Microsoft ODBC for Oracle};Server=ORACLE8i7;
Persist Security Info=False;Trusted_Connection=yes");
OdbcConnection conn = new OdbcConnection(
"Driver={Microsoft Access Driver (*.mdb)};DBQ=c:\bin\nwind.mdb");
OdbcConnection conn = new OdbcConnection(
"Driver={Microsoft Excel Driver (*.xls)};DBQ=c:\bin\book1.xls");
OdbcConnection conn = new OdbcConnection(
"Driver={Microsoft Text Driver (*.txt; *.csv)};DBQ=c:\bin");
OdbcConnection conn = new OdbcConnection("DSN=dsnname");
更多字符串连接说明请看MSDN：
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfSystemDataOdbcOdbcConnectionClassConnectionStringTopic.asp?frame=true
其他厂商提供的数据库连接：
DB2Connection myConn = new IBM.Data.DB2.DB2Connection(
"DATABASE = SAMPLE;UID=<username; PWD=<password;");
DB2Connection myConn = new IBM.Data.DB2.DB2Connection("DATABASE = SAMPLE");
BdpConnection myConn = new Borland.Data.Provider.BdpConnection("assembly=Borl
and.Data.MSSQL,Version=1.1.0.0,Culture=neutral,PublicKeyToken=91d62ebb5b0d1b1b;ve
ndorclient=sqloledb.dll;osauthentication=False;database=<database;usernam
e=<user;hostname=<host;password=<password;provider=MSSQL");
BdpConnection myConn = new Borland.Data.Provider.BdpConnection("assembly=Borl
and.Data.Db2,Version=1.1.0.0,Culture=neutral,PublicKeyToken=91d62ebb5b0d1b1b;ve
ndorclient=db2cli.dll;database=<database;username=<user;
password=<password;provider=DB2");
Connection Pooling
在SQL Server、OLE DB和.NET框架结构中的Data Provider中，都提供了隐式的连接池连接支持。
你可以在ConnectionString中指定不同的参数值控制连接池的行为。比如下面的例子使OLE DB的连接池无效并自动地进行事务处理：
Provider=SQLOLEDB;OLE DB Services=-4;Data Source=localhost;Integrated Security=SSPI;
在SQL Server.NET Data Provider中提供了以下参数设置控制连接池的行为：Connection Lifttime、Connection Reset、Enlist、Max Pool Size、Min Pool Size和Pooling。
