相交MySQL的使用可比列

Question

我想使用MySQL創建以下兩個查詢的交集：

1) SELECT atn_nid, atn_select_flag, atn_image_name 
FROM city, attraction WHERE cty_nid = atn_cty_nid AND cty_nid = 5; 

2) SELECT atn_nid, s2a_image_select_flag, atn_image_name 
FROM segment, seg2atn, attraction WHERE seg_nid = s2a_seg_nid AND 
s2a_atn_nid = atn_nid and seg_nid = 68 AND 
s2a_image_select_flag = true; 

注：查詢1 atn_select_flag和s2a_image_select_flag都是布爾

由於MYSQL由於某些原因不支持INTERSECT，我不知道用什麼語法來完成這個任務。任何幫助將不勝感激。

Answer 1

如果我認爲正確的是：

• 領域命名atn_...，cty_...，seg_...和s2a_...到attraction，city，segment和seg2atn，分別屬於。
• 字段名爲..._nid是主鍵。
• atn_cty_nid,s2a_seg_nid等是外鍵。

那麼你的第一個查詢是相同的：

SELECT atn_nid, atn_select_flag, atn_image_name 
    FROM attraction 
WHERE aty_cty_nid = 5 
; 

和你的第二個查詢是相同的：

SELECT atn_nid, TRUE, atn_image_name 
    FROM attraction 
WHERE atn_id IN 
     (SELECT s2a_atn_nid 
      FROM seg2atn 
      WHERE s2a_seg_nid = 68 
      AND s2a_image_select_flag = TRUE 
     ) 
; 

所以它們的交集是這樣的：

SELECT atn_nid, TRUE AS atn_select_flag, atn_image_name 
    FROM attraction 
WHERE atn_cty_nid = 5 
    AND atn_nid IN 
     (SELECT s2a_atn_nid 
      FROM seg2atn 
      WHERE s2a_seg_nid = 68 
      AND s2a_image_select_flag = TRUE 
     ) 
; 

和（編輯補充）他們的工會是這樣的：

SELECT atn_nid, atn_select_flag, atn_image_name 
    FROM attraction 
WHERE aty_cty_nid = 5 
UNION 
SELECT atn_nid, TRUE, atn_image_name 
    FROM attraction 
WHERE atn_id IN 
     (SELECT s2a_atn_nid 
      FROM seg2atn 
      WHERE s2a_seg_nid = 68 
      AND s2a_image_select_flag = TRUE 
     ) 
;