MySQL - 在另一個UNION查詢中使用查詢結果

Question

如何將我從一個查詢中獲得的結果應用到另一個查詢中，我將與UNION加入？我試圖通過一次使用SQL查詢來刪除根鏈接及其所有子節點。我當然可以得到結果，然後用PHP做另一個查詢調用，但是如果可能的話，不要這樣做。到目前爲止，我來到這個代碼不工作：

SELECT id AS layer1 
FROM AdminNavigation 
WHERE id = 1 

UNION 

SELECT id AS layer2 
FROM AdminNavigation 
WHERE parentId = layer1 

UNION 

SELECT id AS layer3 
FROM AdminNavigation 
WHERE parentId = layer2 

Answer 1

SELECT id AS layer1 
FROM AdminNavigation 
WHERE id = 1 

UNION 

SELECT id AS layer2 
FROM AdminNavigation 
WHERE parentId in(SELECT id 
FROM AdminNavigation 
WHERE id = 1 
) 

UNION 

SELECT id AS layer3 
FROM AdminNavigation 
WHERE parentId in (
SELECT id 
FROM AdminNavigation 
WHERE parentId in(SELECT id 
FROM AdminNavigation 
WHERE id = 1 
)) 

你不能簡單地把內部查詢一樣簡單解析。 正如我在上面的查詢中試過的。

希望這會有所幫助