到`IN`添加條件查詢

Question

查詢：

SELECT * FROM #__content WHERE featured=1 and catid=$category_id or catid IN 
(SELECT id FROM #__categories WHERE parent_id=$category_id) 

Featured=1作品只有在這裏catid=$category_id。 catid IN (SELECT id FROM #__categories WHERE parent_id=$category_id)開始輸出所有行，並且特徵= 1的位置在此處被忽略。如何增加featured=1條件到catid IN？

所以基本上它看起來像這樣由現在：

$query = "SELECT * FROM #__content WHERE featured=1 and catid=$category_id"; 
$query2 = "SELECT * FROM #__content WHERE catid IN 
    (SELECT id FROM #__categories WHERE parent_id=$category_id)"; 

Answer 1

您需要添加括號強制評估的，你需要的順序：

SELECT * FROM #__content WHERE catid=$category_id OR (featured=1 AND catid IN 
(SELECT id FROM #__categories WHERE parent_id=$category_id)) 

由於AND比OR更高的優先級，當(featured=1 and catid=$category_id)爲真或catid位於由子查詢指定的IN列表中時，沒有括號的表達式爲真。

Answer 2

加入怎麼樣？

$query = "SELECT * FROM #__content WHERE featured=1 and catid=$category_id"; 
$query2 = " 
SELECT * FROM #__content as con 
LEFT JOIN #__categories as cat 
on con.cat_id =cat.category_id 
WHERE cat.parent_id=$category_id;"