MYSQL - 'SELECT'和'AS只能創建一列。如何讓它們變得更多？

Question

我有這樣一個查詢：

SELECT (SELECT name FROM text WHERE id = 100) as name, x, y, w, h FROM pictures WHERE id_obj = 'example' AND picture_type = 20 ORDER BY id DESC LIMIT 1 

它工作正常，只要有一個從圖片表符合條件的任何一行。不幸的是（對我來說很明顯爲什麼），當沒有picture_type = 20和id_obj ='example'時，雖然在'text'表中有id = 100的行，但它會產生空結果。

問題是：如何從'文本'表中選擇名稱，無論圖片類型和id_obj是否存在於'圖片'表中？

我發現了這樣的查詢，但我不喜歡它（它太複雜，看起來可怕:)

SELECT 
(SELECT name FROM text WHERE id = 100) as name, 
(SELECT x FROM pictures WHERE id_obj = 'example' AND picture_type = 20) as x, 
(SELECT y FROM pictures WHERE id_obj = 'example' AND picture_type = 20) as y, 
(SELECT w FROM pictures WHERE id_obj = 'example' AND picture_type = 20) as w, 
(SELECT h FROM pictures WHERE id_obj = 'example' AND picture_type = 20) as h, 
(SELECT id FROM pictures WHERE id_obj = 'example' AND picture_type = 20) as id 
ORDER BY id DESC LIMIT 1 

我能讓它更乾淨？ 在此先感謝。

Answer 1

左嘗試加入，應該很好地工作：

SELECT t.name, p.x, p.y, p.w, p.h FROM text t 
LEFT JOIN pictures p ON p.id_obj = 'example' AND p.picture_type = 20 
WHERE t.id = 100