NHibernate连接多数据库字符定义问题

在用NHibernate1.2.0.GA版本中自带的NHibernate.Examples-2.0下的QuickStart测试连接Oracle数据库时，一直提示：System.Data.OracleClient.OracleException : ORA-12704: character set mismatch，但如果改成连接SqlServer数据库，一切OK。

Config文件中的配置如下：

< nhibernate >
     < add key = " hibernate.connection.provider "  value = " NHibernate.Connection.DriverConnectionProvider "   />
     < add key = " hibernate.dialect "  value = " NHibernate.Dialect.OracleDialect "   />
     < add key = " hibernate.connection.driver_class "  value = " NHibernate.Driver.OracleClientDriver "   />
     < add key = " hibernate.connection.connection_string "  value = " Data Source=dev;User ID=hcp;Password=hcp; "   />
   </ nhibernate >

User.hbm.xml文件中的配置如下：

<? xml version = " 1.0 "  encoding = " utf-8 "   ?>

< hibernate - mapping xmlns = " urn:nhibernate-mapping-2.2 " >

 

   < class  name = " NHibernateTest.User,NHibernateTest "  table = " users "  lazy = " false " >

     < id name = " Id "  column = " LogonId "  type = " String "  length = " 128 " >

       < generator  class = " assigned "   />

     </ id >

 

     < property name = " UserName "  column = " Name "  type = " String "  length = " 128 " />

     < property name = " Password "  type = " String "  length = " 128 " />

     < property name = " EmailAddress "  type = " String "  length = " 128 " />

     < property name = " LastLogon "  type = " DateTime " />

   </ class >

 

</ hibernate - mapping >

 

在网上找了很久也没有找到这方面的错误信息，后来我查看了NHibernate的源码，在Type下发现了另外一种类型：AnsiString，这让我立即想起在使用Castle连接Oracle时，是使用的AnsiString类型，故把User.hbm.xml改成如下：

 

<? xml version = " 1.0 "  encoding = " utf-8 "   ?>

< hibernate - mapping xmlns = " urn:nhibernate-mapping-2.2 " >

 

   < class  name = " NHibernateTest.User,NHibernateTest "  table = " users "  lazy = " false " >

     < id name = " Id "  column = " LogonId "  type = " AnsiString "  length = " 128 " >

       < generator  class = " assigned "   />

     </ id >

 

     < property name = " UserName "  column = " Name "  type = " AnsiString "  length = " 128 " />

     < property name = " Password "  type = " AnsiString "  length = " 128 " />

     < property name = " EmailAddress "  type = " AnsiString "  length = " 128 " />

     < property name = " LastLogon "  type = " DateTime " />

   </ class >

 

</ hibernate - mapping >

 

用NUnit测试，立即成功。

 

问题虽然已经解决，但我又想到另外一个问题，因为在使用NHibernate时，每一个实体类都对应一个*.hbm.xml，那在开发支持多数据库应用时，字符类型不就会出现在使用SqlServer 时使用String类型，在使用Oracle时使用AnsiString了吗？不知道这个问题大家是如何解决的，请高人指点，先谢了！