如何編寫此SQL SELECT查詢？

Question

說我有兩張桌子。 new_dogs和name_color_pairs。

name_color_pairs中的記錄必須是唯一對。

new_dogs
---------
Name
Location Found
Color
Breed


name_color_pairs
---------
name
color

如何從new_dogs中選擇當前不在name_color_pairs表中的名稱/顏色對，以便可以插入它們？

Answer 1

SELECT name, color FROM new_dogs
EXCEPT
SELECT name, color FROM name_color_pairs

要么

SELECT name, color FROM new_dogs nd
WHERE NOT EXISTS (SELECT name, color FROM name_color_pairs ncp WHERE (ncp.name = nd.name) AND (ncp.color = nd.color))

或者最后（應該到處工作）：

SELECT name, color FROM new_dogs nd
LEFT JOIN name_color_pairs ncp
ON (ncp.color = nd.color) AND (ncp.name = nd.name)
WHERE ncp.name IS NULL