CODEWITHSUNDEEP
mysqlsqldatabasedatabase-designdatabase-schema
Archit Arora
Archit Arora

Reputation: 2626

Combining two tables in a database

I have made two tables. The first table holds the metadata of a file.

create table filemetadata (
id varchar(20) primary key ,
filename varchar(50),
path varchar(200),
size varchar(10),
author varchar(50)
) ;

+-------+-------------+---------+------+---------+
| id    | filename    | path    | size | author  | 
+-------+-------------+---------+------+---------+
| 1     | abc.txt     | c:\files| 2kb  | eric    | 
+-------+-------------+---------+------+---------+
| 2     | xyz.docx    | c:\files| 5kb  | john    | 
+-------+-------------+---------+------+---------+
| 3     | pqr.txt     |c:\files | 10kb | mike    | 
+-------+-------------+---------+------+---------+

The second table contains the "favourite" info about a particular file in the above table.

create table filefav (
fid varchar(20) primary key ,
id varchar(20),
favouritedby varchar(300),
favouritedtime varchar(10),
FOREIGN KEY (id) REFERENCES filemetadata(id) 
) ;

+--------+------+-----------------+----------------+
| fid    | id   | favouritedby    | favouritedtime | 
+--------+------+-----------------+----------------+
| 1      | 1    | ross            | 22:30          | 
+--------+------+-----------------+----------------+
| 2      | 1    | josh            | 12:56          | 
+--------+------+-----------------+----------------+
| 3      | 2    | johny           | 03:03          | 
+--------+------+-----------------+----------------+
| 4      | 2    | sean            | 03:45          | 
+--------+------+-----------------+----------------+

here "id' is a foreign key. The second table is showing which person has marked which document as his/her favourite. Eg the file abc.txt represented by id = 1 has been marked favourite (see column favouritedby) by ross and josh.

so what i wanna do is to get a table/view which shows the info as following - 

+-------+-------------+---------+------+---------+---------------+
| id    | filename    | path    | size | author  | favouritedby  |
+-------+-------------+---------+------+---------+---------------+
| 1     | abc.txt     | c:\files| 2kb  | eric    | ross, josh    |
+-------+-------------+---------+------+---------+---------------+
| 2     | xyz.docx    | c:\files| 5kb  | john    | johny, sean   |
+-------+-------------+---------+------+---------+---------------+
| 3     | pqr.txt     |c:\files | 10kb | mike    | NULL          |
+-------+-------------+---------+------+---------+---------------+

How do i achieve this?

Upvotes: 1

Views: 83

Answers (3)

Bart Friederichs
Bart Friederichs

Reputation: 33511

Use JOIN (from the top of my head, no checks done):

SELECT filemetadata.id, filename, path, size, author, GROUP_CONCAT(favouritedby) 
FROM filemetadata 
LEFT JOIN filefav ON filemetadata.id=filefav.id GROUP BY filemetadata.id

Upvotes: 3

Amit Singh
Amit Singh

Reputation: 8109

Select A.*,B.favouritedby FROM filemetadata A Left join (Select id,Group_Concat(favouritedby) from filefav group by id) B ON A.Id=B.Id

Upvotes: 2

dude
dude

Reputation: 4962

Create a view that creates a UNION of the two tables:

CREATE VIEW filefavs AS
SELECT * FROM filemetadata 
UNION
SELECT * FROM filefav

Upvotes: -1

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