帶連接的Mysql查詢

Question

我無法進行查詢以獲取某些交叉值。我對mysql的瞭解不太適合做這種事情。

我有兩個表，signedup和signedupLocal。兩者具有相同的字段：名稱，姓氏1，姓氏2，NIF，年份，城市，狀態和日期簽名。

我希望兩個表中的所有值都在狀態爲0時同時按surname1和surname2（A到Z）順序排列。此外，我希望有一個新的字段，例如「app」，它根據數據來自哪個表，說是或否。如果signedpupLocal，yes else no。

之後，我想在狀態爲1的時候按照dateSigned（老的第一個）排序來做同樣的事情。

我還沒有嘗試去測試一個完整的查詢，因爲我只有一部分的問題。

我已經嘗試過類似：

SELECT signedupLocal.name, 
     signedupLocal.surname1, 
     signedupLocal.surname2, 
     signedupLocal.NIF, 
     signedupLocal.year, 
     signedupLocal.city, 
     signedup.name, 
     signedup.surname1, 
     signedup.surname2, 
     signedup.NIF, 
     signedup.year, 
     signedup.city 
FROM signedup, signedupLocal 
WHERE signedup.id_Event = 78 
AND signedupLocal.id_Event = 78 
AND signedupLocal.status = 0 
AND signedup.status = 0 

但它失敗。

Answer 1

SELECT name, surname1, surname2, NIF, year, city, status, 'no' as app, 
     case when status = 1 then datesigned else '2099-12-31' end as datesigned_sort, 
     case when status = 0 then surname1 else '' end as surname1_sort, 
     case when status = 0 then surname2 else '' end as surname2_sort 
FROM signedup 
WHERE id_Event = 78 AND status in(0,1) 

UNION ALL 

SELECT name, surname1, surname2, NIF, year, city, status, 'yes' as app, 
     case when status = 1 then datesigned else '2099-12-31' end as datesigned_sort, 
     case when status = 0 then surname1 else '' end as surname1_sort, 
     case when status = 0 then surname2 else '' end as surname2_sort 
FROM signedupLocal 
WHERE id_Event = 78 AND status in(0,1) 

ORDER BY 7 asc, 9 desc, 10 asc, 11 asc 

注意事項使用UNION時，你需要在ORDER BY使用列數字，而不是列名。我使用UNION ALL，因爲它比UNION更高效，因爲後者刪除重複項 - 這會導致數據庫引擎的工作量。所以如果你知道沒有，你可以避免這種情況。

對於排序，我使用一個常數的情況下，記錄不應該按排序列排序。

Answer 2

使用2個查詢中的UNION來連接結果。

SELECT * FROM (
SELECT *, "signedup" AS tablename FROM signedup WHERE … 
UNION 
SELECT *, "signedupLocal" AS tablename FROM signedupLocal WHERE … 
) U 
ORDER BY U.dateSigned DESC