MySQL子查询循环每行返回

这使用两个查询，我喜欢得到第一个子查询中返回的每一行返回的结果，这将运行第二个查询，本质上这将像一个foreach循环。我希望有人能够很快得出这个结论。MySQL子查询循环每行返回

CREATE TABLE `File_Structure`(
    `id` INT PRIMARY KEY AUTO_INCREMENT, 
    `name` VARCHAR(255) NOT NULL DEFAULT '', 
    `is_folder` TINYINT(1) NOT NULL DEFAULT 0, 
    `lft` INT NOT NULL DEFAULT 0, 
    `rht` INT NOT NULL DEFAULT 0, 
    `is_active` TINYINT(1) NOT NULL DEFAULT 1, 
    `created` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP, 
    `modified` DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00' 
)ENGINE=InnoDB; 
INSERT INTO `file_structure` (`id`, `name`, `is_folder`, `lft`, `rht`, `is_active`, `created`, `modified`) VALUES 
    (1, 'Code', 1, 1, 12, 1, '2017-11-26 00:13:40', '0000-00-00 00:00:00'), 
    (2, 'Account', 1, 2, 7, 1, '2017-11-26 00:13:40', '0000-00-00 00:00:00'), 
    (3, 'AccountCreate.php', 0, 3, 4, 1, '2017-11-26 00:13:40', '0000-00-00 00:00:00'), 
    (4, 'AccountsFindAll.php', 0, 5, 6, 1, '2017-11-26 00:13:40', '0000-00-00 00:00:00'), 
    (5, 'JournalEntry', 1, 8, 11, 1, '2017-11-26 00:13:41', '0000-00-00 00:00:00'), 
    (6, 'JournalCreate.php', 0, 9, 10, 1, '2017-11-26 00:13:41', '0000-00-00 00:00:00'); 

-- 1. FIND ALL LEAF NODES OF A DESIRED NODE. 
SELECT `name` 
FROM `File_Structure` AS `MAIN`, 
(
    SELECT `lft`, `rht` 
    FROM 
    `File_Structure` 
    WHERE `name`='Account' 
) AS `SUB` 
WHERE `MAIN`.`lft`>`SUB`.`lft` 
AND `MAIN`.`rht`<`SUB`.`rht` 
AND `MAIN`.`rht`=`MAIN`.`lft`+1 
; 
-- 2. FOR A LEAF NODE, GET A PATH UPTO THE DESIRED NODE. 
//SET group_concat_max_len = 2048 TO AVOID THE LIMIT OF 1K STRING LENGTH. 

SELECT GROUP_CONCAT(`SUB`.`name` SEPARATOR '/') AS `CONCATEDNAME` 
FROM 
(
    SELECT `PARENT`.`name` 
    FROM `File_Structure` AS `NODE`, 
    `File_Structure` AS `PARENT` 
    WHERE `NODE`.`lft` BETWEEN `PARENT`.`lft` AND `PARENT`.`rht` 
    AND `NODE`.`name` = 'AccountsFindAll.php' 
    ORDER BY `PARENT`.`lft` 
) AS `SUB` 
; 

-- 3. REPEAT 2 FOR 1

来源

2017-11-25 observo

什么是你的问题？ – Blag

非常感谢您在您的问题中包含CREATE TABLE和一些示例数据。这是询问SQL问题的最佳方式，很少有人在他们的问题中包含这些所需的细节。 –

谢谢你，比尔。我看到你是一个极端的专家，因此这是一个非常愉快的诉诸于计算器。非常感谢你。 – observo

它更容易使用JOIN比各级子查询：

SELECT GROUP_CONCAT(path.name ORDER BY path.lft SEPARATOR '/') AS CONCATEDNAME 
FROM File_Structure AS root 
JOIN File_Structure AS leaf ON leaf.lft BETWEEN root.lft AND root.rht 
JOIN File_Structure AS path ON leaf.lft BETWEEN path.lft AND path.rht 
WHERE leaf.rht = leaf.lft+1 
AND root.name='Account' 
GROUP BY leaf.name;

输出：

+----------------------------------+ 
| CONCATEDNAME      | 
+----------------------------------+ 
| Code/Account/AccountCreate.php | 
| Code/Account/AccountsFindAll.php | 
+----------------------------------+

来源

2017-11-25 20:26:33

MySQL子查询循环每行返回

回答

相关问题