NHibernate HQL Generator支持SQL Server 2016时态表

Question

我试图在NHibernate 4.x中实现对SQL Server 2016时态表的基本支持.想法是改变SQL语句

SELECT * FROM Table t0

至

SELECT * FROM Table FOR SYSTEM_TIME AS OF '2018-01-16 00:00:00' t0

您可以在此处找到有关SQL Server 2016中时态表的更多信息

不幸的是,我没有找到任何方法FOR FOR SYSTEM_TIME AS OF '...'在表名和它的别名之间插入语句.我不确定自定义方言是否支持此功能.我现在唯一可行的解​​决方案是FOR SYSTEM_TIME在extra中附加语句WHERE,我的输出SQL看起来像这样

SELECT * FROM Table t0 WHERE FOR SYSTEM_TIME AS OF '2018-01-16 00:00:00'=1

为此,我实现了生成器和方言,如下所示:

public static class AuditableExtensions
{
    public static bool AsOf(this IAuditable entity, DateTime date)
    {
        return true;
    }

    public static IQueryable<T> Query<T>(this ISession session, DateTime asOf) where T : IAuditable
    {
        return session.Query<T>().Where(x => x.AsOf(asOf));
    }
}

public class ForSystemTimeGenerator : BaseHqlGeneratorForMethod
{
    public static readonly string ForSystemTimeAsOfString = "FOR SYSTEM_TIME AS OF";

    public ForSystemTimeGenerator()
    {
        SupportedMethods = new[]
        {
            ReflectionHelper.GetMethod(() => AuditableExtensions.AsOf(null, DateTime.MinValue))
        };
    }

    public override HqlTreeNode BuildHql(MethodInfo method, Expression targetObject, 
        ReadOnlyCollection<Expression> arguments,
        HqlTreeBuilder treeBuilder, 
        IHqlExpressionVisitor visitor)
    {
        return treeBuilder.BooleanMethodCall(nameof(AuditableExtensions.AsOf), new[]
        {
            visitor.Visit(arguments[1]).AsExpression()
        });
    }
}

public class MsSql2016Dialect : MsSql2012Dialect
{
    public MsSql2016Dialect()
    {
        RegisterFunction(nameof(AuditableExtensions.AsOf), new SQLFunctionTemplate(
            NHibernateUtil.Boolean, 
            $"{ForSystemTimeGenerator.ForSystemTimeAsOfString} ?1?2=1"));
    }
}

任何人都可以提供任何更好的方法或样本,我可以用它来前进并FOR SYSTEM_TIME AS OF在表名和它的别名之间插入语句吗？在这一刻,我能看到的唯一解决方案是改进SQL OnPrepareStatement,SessionInterceptor但我相信有一些更好的方法......

Answer 1

DECLARE @String1 NVARCHAR(100),
    @String2 NVARCHAR(100) ,
    @DateTime DATETIME= '2018-01-16 00:00:00';

 SET @String1 = 'SELECT * FROM Table2';
 SET @String2 = @String1 + ' FOR SYSTEM_TIME AS OF '''
 + CONVERT(VARCHAR(20), @DateTime, 120) + '''';
 SELECT  @String2;