sql执行原理详解（Sql server中内部函数fn_PhysLocFormatter存在解析错误详解）

select SiteID,%%physloc%%,sys.fn_PhysLocFormatter(%%physloc%%) from NT_SiteInfo

dbcc ind(wjgk,nt_siteinfo,0)

select OBJECT_DEFINITION(object_id('sys.fn_PhysLocFormatter'))
go
 
-------------------------------------------------------------------------------
-- Name: sys.fn_PhysLocFormatter
--
-- Description:
-- Formats the output of %%physloc%% virtual column
--
-- Notes:
-------------------------------------------------------------------------------
create function sys.fn_PhysLocFormatter (@physical_locator binary (8))
 returns varchar (128)
as
 begin
 declare @page_id binary (4)
 declare @file_id binary (2)
 declare @slot_id binary (2)
 -- Page ID is the first four bytes, then 2 bytes of page ID, then 2 bytes of slot
 --
 select @page_id = convert (binary (4), reverse (substring (@physical_locator, 1, 4)))
 select @file_id = convert (binary (2), reverse (substring (@physical_locator, 5, 2)))
 select @slot_id = convert (binary (2), reverse (substring (@physical_locator, 7, 2)))
 return '(' + cast (cast (@file_id as int) as varchar) + ':'
 + cast (cast (@page_id as int) as varchar) + ':'
 + cast (cast (@slot_id as int) as varchar) + ')'
 end

select reverse('工人')
----
人工
 
(1 行受影响)
 
select reverse('12345工人')
---------
人工54321
 
(1 行受影响)
 
select reverse('工12345人')
---------
人54321工
 
(1 行受影响)