我碰到、想到和回答过的NHibernate里的不能单独成文的小知识点，持续更新。

 Q:不设置Cache时NHibernate会使用二级缓存吗

A:会，它会使用NHibernate.Cache.HashtableCacheProvider

 
Q:配置文件中use_outer_join和max_fetch_depth有什么作用

A:当使用关联影射时，如果未设置延迟加载，如果use_outer_join为true,则NHibernate用带join的Sql同时读取对象；为false,则分两条Sql读取。

max_fetch_depth表示最多join几个对象。

Q:查询时如何分页

A:使用ICriteria时

ISession session=factory.OpenSession();
ICriteria criteria=session.CreateCriteria(typeof(News));
criteria.SetFirstResult(fromResult);
criteria.SetMaxResults(count);
return criteria.List();

使用IQuery时

IQuery query = Session.CreateQuery(hql);
query.SetFirstResult(fromResult);
query.SetMaxResults(count); 
return query.List();

SetFirstResult设置从那天记录开始，SetMaxResults设置取几条数据

 
Q:Sql2005有dialect吗

A:有，NHibernate论坛可以找到，单独的文件，以后版本可能会加入NHibernate内部。

MsSql2005Dialect.
using System.Text;
using NHibernate.SqlCommand;

namespace NHibernate.Dialect
{
    public class MsSql2005Dialect : MsSql2000Dialect
    {
        public override SqlString GetLimitString(SqlString querySqlString, int offset, int last)
        {
            /**//*
             * WITH query AS
             *     (SELECT TOP last ROW_NUMBER() OVER (ORDER BY orderby) as __hibernate_row_nr__,  original_query)
             * SELECT * 
             * FROM query
             * WHERE __hibernate_row_nr__ > offset
             * ORDER BY __hibernate_row_nr__
             */
            SqlStringBuilder pagingBuilder = new SqlStringBuilder();
            StringBuilder orderByStringBuilder = new StringBuilder();
            string distinctStr = string.Empty;

            foreach (object sqlPart in querySqlString.SqlParts)
            {
                string sqlPartString = sqlPart as string;
                if (sqlPartString != null)
                {
                    string loweredString = sqlPartString.ToLower();
                    int orderByIndex = loweredString.IndexOf("order by");
                    if (orderByIndex != -1)
                    {
                        // if we find a new "order by" then we need to ignore
                        // the previous one since it was probably used for a subquery
                        orderByStringBuilder = new StringBuilder();
                        orderByStringBuilder.Append(sqlPartString.Substring(orderByIndex));
                    }
                    if (loweredString.TrimStart().StartsWith("select"))
                    {
                        int index = 6;
                        if (loweredString.StartsWith("select distinct"))
                        {
                            distinctStr = "DISTINCT ";
                            index = 15;
                        }
                        sqlPartString = sqlPartString.Substring(index);
                    }

                    pagingBuilder.Add(sqlPartString);
                }
                else
                {
                    pagingBuilder.AddObject(sqlPart);
                }
            }

            string orderby = orderByStringBuilder.ToString();
            // if no ORDER BY is specified use fake ORDER BY field to avoid errors 
            if (orderby == null || orderby.Length == 0)
                orderby = "ORDER BY CURRENT_TIMESTAMP";

            string beginning =
                string.Format("WITH query AS (SELECT {0}TOP {1} ROW_NUMBER() OVER ({2}) as __hibernate_row_nr__, ",
                              distinctStr, last, orderby);
            string ending =
                string.Format(") SELECT * FROM query WHERE __hibernate_row_nr__ > {0} ORDER BY __hibernate_row_nr__",
                              offset);

            pagingBuilder.Insert(0, beginning);
            pagingBuilder.Add(ending);

            return pagingBuilder.ToSqlString();
        }

        public override bool SupportsLimit
        {
            get { return true; }
        }

        public override bool SupportsLimitOffset
        {
            get { return true; }
        }
    }
}

Q:Access有dialect吗

A:NHibernateContrib里面有NHibernate.JetDriver.JetDialect


Q:Guid的unsaved-value怎么设置
A:unsaved-value="00000000-0000-0000-0000-000000000000"