CODEWITHSUNDEEP
mysqldatabaseselectjoin
jojo
jojo

Reputation: 134

Merge data from 2 tables in MySQL

I have 2 tables folder structure like this in MySQL:

folders Table: 

|folder_id | folder_parent_id | folder_name | is_active|
+----------+------------------+-------------+----------+
|     1    |       NULL       |   Desktop   |     1    |
|     2    |       NULL       |  Downloads  |     1    |
|     3    |        2         |   Movies    |     1    |
|     4    |        2         |   Musics    |     0    |
|     5    |        1         |   Trash     |     1    |
|     6    |       NULL       |   Systems   |     1    |
|     7    |       NULL       |   Locals    |     0    |

documents Table: 

|document_id |  folder_id | document_name | document_status   |
+------------+------------+---------------+-------------------+
|     1      |     NULL   |    Invoice    |     approved      |
|     2      |      3     |    Subtitle   |     approved      |
|     3      |      4     |    Lyrics     |    not_approved   |
|     5      |      6     |    ReadME     |     approved      | 
|     6      |      2     |    Script     |     approved      |

So basically this two tables are for my file manager system,i need to retrieve the folder and documents based on the folder_parent_id, this column is to mark if a folder is inside another folder so the another folder will be the parent. if the folder_parent_id is NULL it means the folder is in the root of the directory. As for the document it can be inside another folder or in the root directory (folder_id is null). What i want to achieve is to get a select data like this:

for example in case of folder_parent_id is NULL AND is_active = 1 :

|folder_id | folder_name |  document_id |document_status|document_name|
|----------+-------------+--------------+---------------+-------------+
|    1     |   Desktop   |   NULL       |    NULL       |   NULL      |
|    2     |   Downloads |   NULL       |    NULL       |   NULL      |
|    6     |   Systems   |   NULL       |    NULL       |   NULL      |
|   NULL   |   NULL      |   1          |    approved   |   Invoice   |

for example in case of folder_parent_id is 2 AND is_active = 1 :

|folder_id | folder_name |  document_id |document_status|document_name|
|----------+-------------+--------------+---------------+-------------+
|    3     |   Movies    |   NULL       |    NULL       |   NULL      |
|    4     |   Musics    |   NULL       |    NULL       |   NULL      |
|   NULL   |   NULL      |   6          |    approved   |   Script    |

it will select all the folders and files with column like that

Upvotes: 0

Views: 50

Answers (1)

Marco
Marco

Reputation: 57573

If I understand what you want, I think you need something like this:

SELECT folder_id, folder_name, 
    NULL AS document_id, NULL as document_status, NULL as document_name
FROM folders 
WHERE folder_parent_id = your_number AND is_active = 1

UNION

SELECT NULL as folder_id, NULL as folder_name,
    document_id, document_status, document_name
FROM documents 
WHERE folder_id = your_number AND is_active = 1

Upvotes: 1

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