需要一些自我加入問題的認真幫助

Question

就像你可能知道的那樣，你不能通過自聯接爲一個視圖建立索引。實際上，甚至連同一張表的兩個連接，即使它不是技術上的自連接。微軟的幾個人提出了一個解決方案。但它太複雜了，我不明白！

的問題的解決方案是在這裏：http://jmkehayias.blogspot.com/2008/12/creating-indexed-view-with-self-join.html

我想圍繞應用這項工作的視圖是：

create VIEW vw_lookup_test 
WITH SCHEMABINDING 
AS 
select 
count_big(*) as [count_all], 
awc_txt, 
city_nm, 
str_nm, 
stru_no, 
o.circt_cstdn_nm [owner], 
t.circt_cstdn_nm [tech], 
dvc.circt_nm, 
data_orgtn_yr 
from 
((dbo.dvc 
join dbo.circt 
on dvc.circt_nm = circt.circt_nm) 
join dbo.circt_cstdn o 
on circt.circt_cstdn_user_id = o.circt_cstdn_user_id) 
join dbo.circt_cstdn t 
on dvc.circt_cstdn_user_id = t.circt_cstdn_user_id 
group by 
awc_txt, 
city_nm, 
str_nm, 
stru_no, 
o.circt_cstdn_nm, 
t.circt_cstdn_nm, 
dvc.circt_nm, 
data_orgtn_yr 
go 

任何幫助將大大apreciated！

非常感謝！

編輯：所以我發現這也將工作。請注意，我在第一個索引視圖中加入表格一次，第二次在第二個非索引視圖中加入表格。

alter VIEW vw_lookup_owner_test2 
WITH SCHEMABINDING 
AS 
select 
count_big(*) as [countAll], 
awc_txt, 
city_nm, 
str_nm, 
stru_no, 
dvc.circt_nm, 
circt_cstdn_nm, 
data_orgtn_yr, 
dvc.circt_cstdn_user_id 
from dbo.dvc 
join dbo.circt 
on dvc.circt_nm = circt.circt_nm 
join dbo.circt_cstdn o 
on circt.circt_cstdn_user_id = o.circt_cstdn_user_id 
group by 
awc_txt, 
city_nm, 
str_nm, 
stru_no, 
dvc.circt_nm, 
circt_cstdn_nm, 
data_orgtn_yr, 
dvc.circt_cstdn_user_id 
go 

和

CREATE UNIQUE CLUSTERED INDEX [idx_vw_lookup_owner2_test1] ON [dbo].[vw_lookup_owner_test2] 
(
    [awc_txt] ASC, 
    [city_nm] ASC, 
    [str_nm] ASC, 
    [stru_no] ASC, 
    [circt_nm] ASC, 
    [circt_cstdn_nm] ASC, 
    [data_orgtn_yr] ASC, 
    [circt_cstdn_user_id] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
GO 

和

create view vw_lookup_dvc_loc 
as 
select 
awc_txt, 
city_nm, 
str_nm, 
stru_no, 
circt_nm, 
o.circt_cstdn_nm as [owner], 
--o.circt_cstdn_user_id, 
t.circt_cstdn_nm as tech, 
data_orgtn_yr 
from vw_lookup_owner_test2 o With (NOEXPAND) 
join circt_cstdn t 
on o.circt_cstdn_user_id = t.circt_cstdn_user_id 
group by 
awc_txt, 
city_nm, 
str_nm, 
stru_no, 
circt_nm, 
o.circt_cstdn_nm, 
data_orgtn_yr, 
t.circt_cstdn_nm 
--o.circt_cstdn_user_id 

然後我可以在第一視圖中創建additon指標如我所願。我不確定此解決方案（或解決方案）是否會提高性能，但我會通知您。

Answer 1

這就是我從博客帖子有

• 比方說，你想加入2倍dbo.circt_cstdn例如，你希望像

    owner  tech 
  rowA  a.nm  b.nm 
  ... 
  

• ，而不是領的值轉換成2列將其分成2行（上面每行爲2行）並添加一個額外的列來說明哪一行是哪一列。請注意該行1.1和1.2行具有相同的數據（除了名稱和列）

    name for 
  row1.1 nm  owner 
  row1.2 nm  tech 
  ... 
  

• 然後你轉動的名稱列的最大業主和技術。注意 - 最大值函數只是欺騙PIVOT（需要一些聚合函數），如果只有一條記錄，則可以使用任何聚合函數返回相同的值 owner tech row1 nm nm ...

現在，如果我們這樣做，爲您的查詢

1. 創建一個表d，像這樣的

   i 
   1 
   2 
   

2. CROSS JOIN查詢與此

   第一部分

   SELECT 
       count_big(*) as [count_all], 
       awc_txt, 
       city_nm, 
       str_nm, 
       stru_no, 
       dvc.circt_nm, 
       data_orgtn_yr 
   FROM 
       dbo.dvc 
       INNER JOIN dbo.circt on dvc.circt_nm = circt.circt_nm 
       CROSS JOIN dbo.d 
   GROUP BY 
       awc_txt, city_nm, str_nm, stru_no, dvc.circt_nm, data_orgtn_yr, d.i 
   

3. 否W¯¯讓我們使用該行的老闆，D.i爲1，高科技如果D.i是2

   SELECT 
       count_big(*) as [count_all], 
       awc_txt, 
       city_nm, 
       str_nm, 
       stru_no, 
       dvc.circt_nm, 
       data_orgtn_yr, 
       Case 
        WHEN d.i = 1 THEN 'Owner' 
        WHEN d.i = 2 THEN 'Tech' 
       END 
   FROM 
       dbo.dvc 
       INNER JOIN dbo.circt on dvc.circt_nm = circt.circt_nm 
       CROSS JOIN dbo.d 
   GROUP BY 
       awc_txt, city_nm, str_nm, stru_no, dvc.circt_nm, data_orgtn_yr, 
       Case 
        WHEN d.i = 1 THEN 'Owner' 
        WHEN d.i = 2 THEN 'Tech' 
       END 
   

4. 現在添加納米柱。要獲取名稱，如果它是所有者行（d.i = 1），則使用circt加入circt_cstdn，如果是tech行（d.i = 2），則使用dvc加入circt_cstdn。注意 - 我通過將這個放在連接條件中來嘗試一個快捷方式。如果它不工作，嘗試博客文章的方式（做circt.circt_cstdn_user_id 或 dvc.circt_cstdn_user_id一個連接，然後使用WHERE子句過濾掉）

   SELECT 
       count_big(*) as [count_all], 
       awc_txt, 
       city_nm, 
       str_nm, 
       stru_no, 
       dvc.circt_nm, 
       data_orgtn_yr, 
       Case 
        WHEN d.i = 1 THEN 'Owner' 
        WHEN d.i = 2 THEN 'Tech' 
       END as PersonType, 
       circt_cstdn_nm 
   FROM 
       dbo.dvc 
       INNER JOIN dbo.circt on dvc.circt_nm = circt.circt_nm 
       CROSS JOIN dbo.d 
       INNER JOIN dbo.circt_cstdn on circt_cstdn_user_id = 
         CASE 
          WHEN d.i = 1 THEN circt.circt_cstdn_user_id 
          WHEN d.i = 2 THEN dvc.circt_cstdn_user_id 
         END 
   GROUP BY 
       awc_txt, city_nm, str_nm, stru_no, dvc.circt_nm, data_orgtn_yr, 
       Case 
        WHEN d.i = 1 THEN 'Owner' 
        WHEN d.i = 2 THEN 'Tech' 
       END, 
       circt_cstdn_nm 
   

5. 使用創建視圖和創建索引

   create VIEW vw_lookup_test_imed 
   WITH SCHEMABINDING 
   AS 
       <<query above>> 
   GO 
   
   spell to create INDEX 
   

6. 現在你PIVOT到PersonType列轉換爲業主和技術列

   SELECT 
       count_all, 
       awc_txt, 
       city_nm, 
       str_nm, 
       stru_no, 
       dvc.circt_nm, 
       data_orgtn_yr, 
       [Owner], 
       [Tech] 
   FROM 
   ( 
       SELECT 
         count_all, 
         awc_txt, 
         city_nm, 
         str_nm, 
         stru_no, 
         dvc.circt_nm, 
         data_orgtn_yr, 
         PersonType, 
         circt_cstdn_nm 
       FROM dbo.vw_lookup_test_imed WITH (NOEXPAND) 
   ) src 
   PIVOT 
   ( 
       MAX(circt_cstdn_nm) 
       FOR PersonType IN ([Owner], [Tech]) 
   ) pvt 
   

如果有語法錯誤（肯定會有很多原因，我現在無法訪問數據庫）請告訴我。

Answer 2

我認爲這個JOIN語法是可怕的，起源於MS Access。啊。 我建議你使用：

select 
count_big(*) as [count_all], 
awc_txt, 
city_nm, 
str_nm, 
stru_no, 
o.circt_cstdn_nm [owner], 
t.circt_cstdn_nm [tech], 
dvc.circt_nm, 
data_orgtn_yr 

-- HERE 
from dbo.dvc 
join dbo.circt on (dvc.circt_nm = circt.circt_nm) 
join dbo.circt_cstdn o on (circt.circt_cstdn_user_id = o.circt_cstdn_user_id) 
join dbo.circt_cstdn t on (dvc.circt_cstdn_user_id = t.circt_cstdn_user_id) 

group by 
awc_txt, 
city_nm, 
str_nm, 
stru_no, 
o.circt_cstdn_nm, 
t.circt_cstdn_nm, 
dvc.circt_nm, 
data_orgtn_yr 

這句法更乾淨，更容易理解和SQL Server，火鳥，甲骨文，MySQL和其他多是公認的。 現在你可以更好地看到「表格」之間的關係。 當您連接兩次或更多次相同的「表」時，您需要爲每個表添加別名。在一行中，「circt_cstdn」被別名爲「o」。在其他行上，「circt_cstdn」的別名爲「t」。

我建議使用LEFT JOIN或INNER JOIN來代替JOIN。