加入一起預連接表，以一個單一的表

Question

我有兩個加入了我以前加入與其他表的表，我想「ddid」與「confid1」

這裏連接起來，代碼如下：

SELECT r.domainid, r.dombegin, r.domend, d.ddid 
FROM domainregion AS r 
JOIN dyndomrun AS d ON r.domainid::varchar(8) = d.ddid 
ORDER BY r.domainid, d.ddid, r.dombegin, r.domend; 

和

(SELECT confid1 as id1, conformer.pdbcode, conformer.chainid 
from dyndomrun JOIN conformer 
      ON dyndomrun.confid1 = conformer.id) 
UNION 
(SELECT confid2 as id2, conformer.pdbcode, conformer.chainid 
from dyndomrun JOIN conformer ON dyndomrun.confid2 = conformer.id) 

最後，我想有含DOMAINID，dombegin，domend，ddid，confid1，pdb號，chainid新表。

這是可能的，因爲當我試着做一個預加入表的聯合時，它給我一個錯誤，說明每個UNION查詢必須具有相同數量的列。

請指教。謝謝。

Answer 1

如果我理解正確：

SELECT 
    r.domainid, 
    r.dombegin, 
    r.domend, 
    d.ddid, 
    d.confid1 AS confid, 
    c.pdbcode, 
    c.chainid 
FROM dyndomrun d 
    INNER JOIN conformer c ON d.confid1 = c.id 
    INNER JOIN domainregion r ON r.domainid::varchar(8) = d.ddid 
UNION ALL 
SELECT 
    NULL, 
    NULL, 
    NULL, 
    d.ddid, 
    d.confid2, 
    c.pdbcode, 
    c.chainid 
FROM dyndomrun d 
    INNER JOIN conformer c ON d.confid2 = c.id 

Answer 2

會不會像這樣的工作？

select domainid, dombegin, domened, ddid, confid_id, pdbcode, chainid 
from (
SELECT r.domainid, r.dombegin, r.domend, d.ddid 
FROM domainregion AS r JOIN dyndomrun AS d ON r.domainid::varchar(8) = d.ddid 
ORDER BY r.domainid, d.ddid, r.dombegin, r.domend 
) first 
inner join (
(SELECT confid1 as confid_id, conformer.pdbcode, conformer.chainid 
from dyndomrun JOIN conformer ON dyndomrun.confid1 = conformer.id) 
UNION 
(SELECT confid2 as confid_id, conformer.pdbcode, conformer.chainid 
from dyndomrun JOIN conformer ON dyndomrun.confid2 = conformer.id) 
) second 
on first.ddid=second.confid_id 

可能會很慢。