hibernate主键生成策略如何选择，数据库 表的ID中有字母 如下图：

SQLServer数据库 下图为Student表。
ps：Student表中StudentNo（数据类型nvarchar（50），非标识列）字段为id，并且与其他表有主外键关系
图片说明

hibernate映射文件：

 <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="com.blue.entity.Student" table="Student" >
        <id name="stuNo" column="StudentNo">
            <generator class=""></generator>
        </id>
        <property name="stuPwd" column="loginPwd"></property>
        <property name="stuName" column="StudentName"></property>
        <property name="stuSex" column="Sex"></property>
        <property name="stuGradeId" column="GradeId"></property>
        <property name="stuPhone" column="Phone"></property>
        <property name="stuAddress" column="Address"></property>
        <property name="stuDate" column="BornDate"></property>
        <property name="stuEmail" column="Email"></property>

    </class>

</hibernate-mapping>

我要向数据库中添加数据（insert），该怎么选择主键生成策略？

不想改数据库，有其他方法吗？

increment、sequence 、identity（支持mysql、sqlserver，不支持oracle）、native、hilo等等，

hibernate主键生成策略，解释的挺全的，好像并没有我想要的（我 字段ID中有字母啊：“as123456”nvarchar（50） 非标识列），
http://www.cnblogs.com/kakafra/archive/2012/09/16/2687569.html

附加：主键生成策略为identity时的报错信息：
生成的sql语句并没有"StudentNo"这一列

 HTTP Status 500 - could not insert: [com.blue.entity.Student]; SQL [insert into Student (loginPwd, StudentName, Sex, GradeId, Phone, Address, BornDate, Email) values (?, ?, ?, ?, ?, ?, ?, ?)]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not insert: [com.blue.entity.Student]

type Exception report

message could not insert: [com.blue.entity.Student]; SQL [insert into Student (loginPwd, StudentName, Sex, GradeId, Phone, Address, BornDate, Email) values (?, ?, ?, ?, ?, ?, ?, ?)]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not insert: [com.blue.entity.Student]

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.dao.DataIntegrityViolationException: could not insert: [com.blue.entity.Student]; SQL [insert into Student (loginPwd, StudentName, Sex, GradeId, Phone, Address, BornDate, Email) values (?, ?, ?, ?, ?, ?, ?, ?)]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not insert: [com.blue.entity.Student]
    org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:643)
    org.springframework.orm.hibernate3.HibernateAccessor.convertHibernateAccessException(HibernateAccessor.java:412)
    org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:411)
    org.springframework.orm.hibernate3.HibernateTemplate.executeWithNativeSession(HibernateTemplate.java:374)
    org.springframework.orm.hibernate3.HibernateTemplate.save(HibernateTemplate.java:683)
    com.blue.dao.impl.StudentDaoImpl.save(StudentDaoImpl.java:21)
    com.blue.service.impl.StudentServiceImpl.save(StudentServiceImpl.java:18)
    com.blue.action.StudentAction.result(StudentAction.java:16)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:606)
    com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:450)
    com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:289)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:252)
    org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
    org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:252)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:161)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
    org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
    org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563)
    org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
    org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)