mysql通過單個查詢獲取結果父ID和類別ID？

Question

我有表，這樣的價值觀，

CREATE TABLE `category` (
`id` INT(4) NOT NULL AUTO_INCREMENT PRIMARY KEY , 
`category` VARCHAR(50) NOT NULL , 
`parent` INT(4) NOT NULL 
) 

INSERT INTO `category` VALUES (1, 'MCA', 9); 
INSERT INTO `category` VALUES (2, 'M Tech', 9); 
INSERT INTO `category` VALUES (3, 'B Tech', 9); 
INSERT INTO `category` VALUES (4, 'BioTech', 9); 
INSERT INTO `category` VALUES (5, 'InfoTech', 9); 
INSERT INTO `category` VALUES (6, 'Chemical', 10); 
INSERT INTO `category` VALUES (7, 'Indus', 10); 
INSERT INTO `category` VALUES (8, 'Physics', 10); 
INSERT INTO `category` VALUES (9, 'Information Science', 0); 
INSERT INTO `category` VALUES (10, 'Others Science', 0); 

我需要的類別和子類別方面獲得的值的單個查詢。第三個值爲零，其他類別爲子類別。

我需要輸出爲樹狀結構這樣，

結果是：

Information Science 
    MCA 
    M Tech 
    B Tech 
    BioTech 
    InfoTech 
Others Science 
    Chemical 
    Indus 
    Physics 

Answer 1

也許這是你想要什麼：

SELECT 
    T1.category AS category, 
    T2.category AS subcategory 
FROM category T1 
JOIN category T2 
ON T1.id = T2.parent 

 
category    subcategory 
'Information Science' 'MCA' 
'Information Science' 'M Tech' 
'Information Science' 'B Tech' 
'Information Science' 'BioTech' 
'Information Science' 'InfoTech' 
'Others Science'  'Chemical' 
'Others Science'  'Indus' 
'Others Science'  'Physics' 

這是假設只有你在你的層次結構中有兩個層次。

Answer 2

Mysql有一個nice article for you。 雖然個人，我會去物化路徑