单一记录表的主从关系查询

数据库的需求真是千差万别,今天遇到的要求比较奇怪,客户数据库是2k版本

-- 测试数据及表结构
if   not   object_id ( ' tempdb..#T ' )  is   null
drop   table  #T
go
if   not   object_id ( ' tempdb..# ' )  is   null
drop   table  #
go
create   table  #T(id  int   identity ( 1 , 1 ),name  char ( 3 ),state  char ( 4 ),time  char ( 8 ),value  decimal ( 5 , 2 ))
go
insert   into  #T 
select   ' AAA '   as  name, ' PASS '   as  state, ' 20081023 '   as  time, null   as  value  union   all
select   ' FGH ' , ' FAIL ' , null , 88.9   union   all
select   ' GHE ' , ' PASS ' , null , 32   union   all
select   ' ABC ' , ' FAIL ' , ' 20080930 ' , null   union   all
select   ' WRH ' , ' FAIL ' , null , 2   union   all
select   ' BBB ' , ' PASS ' , ' 20080101 ' , null   union   all
select   ' CCC ' , ' PASS ' , ' 20080101 ' , null   union   all
select   ' ERT ' , ' PASS ' , null , 33
go
-- 将初步的数据插入临时表#
select  a.id,a.name,a.state,a.time,b.id  as  subid,b.name  as  subname,b.state  as  substate,b.value  into  #
from  #T a  left   join  #T b  on  a.value  is   null   and  b.time  is   null   and  a.id < b.id  where  a.time  is   not   null
-- select * from #
-- 查询语句
select  name,state,time,subname,substate,value  from  # tb
where   not   exists (  select   1   from  #  where  subid = tb.subid  and  id > tb.id)
-- results
AAA    PASS     20081023     FGH    FAIL     88.90
AAA    PASS     20081023     GHE    PASS     32.00
ABC    FAIL     20080930     WRH    FAIL     2.00
CCC    PASS     20080101     ERT    PASS     33.00

上述部分是老需求，现在要把没有子节点的父节点选出来。试验了很久，最终还是只有用cursor，以后有好方法了在更新吧。其实在05里面也可以用CTE来优化查询

if   not   object_id ( ' tempdb..#T ' )  is   null
drop   table  #T
go
if   not   object_id ( ' tempdb..# ' )  is   null
drop   table  #
go
create   table  #T(id  int   identity ( 1 , 1 ),name  char ( 3 ),state  char ( 4 ),time  char ( 8 ),value  decimal ( 5 , 2 ))
go
create   table  #
(name  char ( 3 ),state  char ( 4 ),time  char ( 8 ),subname  char ( 3 ),substate  char ( 4 ),value  decimal ( 5 , 2 ))
go
insert   into  #T 
select   ' AAA '   as  name, ' PASS '   as  state, ' 20081023 '   as  time, null   as  value  union   all
select   ' FGH ' , ' FAIL ' , null , 88.9   union   all
select   ' GHE ' , ' PASS ' , null , 32   union   all
select   ' ABC ' , ' FAIL ' , ' 20080930 ' , null   union   all
select   ' WRH ' , ' FAIL ' , null , 2   union   all
select   ' BBB ' , ' PASS ' , ' 20080101 ' , null   union   all
select   ' CCC ' , ' PASS ' , ' 20080101 ' , null   union   all
select   ' ERT ' , ' PASS ' , null , 33
go
-- select * from #T

declare   @id   int , @time   char ( 8 ), @name   char ( 3 ), @state   char ( 4 ), @value   decimal ( 5 , 2 ), @px   int ;
set   @px = 1 ;
declare  tb_cursor  cursor  LOCAL FORWARD_ONLY KEYSET READ_ONLY  for
select  id,time,name,state,value  from  #T
OPEN  tb_cursor
FETCH  tb_cursor  into   @id , @time , @name , @state , @value

WHILE   @@FETCH_STATUS   =   0
BEGIN
-- 是父节点，而且与上一父节点不相连
if ( @time   is   not   null   and   @id - @px <> 1 )
begin
set   @px = @id
end
-- 是父节点，与上一父节点相连
else   if  ( @time   is   not   null   and   @id - @px = 1 )
begin
insert   into  #  select  name,state,time, null , null , null   from  #T  where  id = @px
set   @px = @id
end
-- 子节点
else
begin
insert   into  #  select  a.name,a.state,a.time,subname = @name ,substate = @state ,value = @value
from  #T a  where  id = @px
end

FETCH  tb_cursor  into   @id , @time , @name , @state , @value
END
-- 关闭并删除cursor
CLOSE  tb_cursor
DEALLOCATE  tb_cursor
-- 查询语句
select   *   from  #
-- result
AAA    PASS     20081023     FGH    FAIL     88.90
AAA    PASS     20081023     GHE    PASS     32.00
ABC    FAIL     20080930     WRH    FAIL     2.00
BBB    PASS     20080101      NULL   NULL      NULL
CCC    PASS     20080101     ERT    PASS     33.00

/**/ /*终于有了
BBB    PASS    20080101    NULL NULL    NULL*/

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