PHP MySQL合并具有相同列值的行

Question

I have a table looks like this:

year | url                | view
-------------------------------
2016 | /document/item.pdf | 21
2015 | /document/item.pdf | 35
2014 | /document/item.pdf | 41

and I want build another table looks like this :

 url                | 2014 | 2015 | 2016
---------------------------------------
 /document/item.pdf | 41   | 35   | 21

I don't really now how I have to write my mysql query to do that. Thanks for your help :)

Answer 1

1. Query all data from your first table to PHP array, the array would be like:

    $data = [[2016, "/document/item.pdf", 21], [2015, "/document/item.pdf", 35], [2014, "/document/item.pdf", 41]]; 

2. Traverse $data , make another associated array $result , whose key is url, value is an array of data with year and view:

    $result = array(); foreach ($data as $value) { $result[$value['url']][$value['year']] = $value['view']; } 

3. Traverse the new array, and write data back to MySQL

Answer 2

You can try this:

 SELECT  url,
            MAX(IF(`year` = 2014 , view, NULL)) '2014',
            MAX(IF(`year` = 2015, view, NULL)) '2015',
            MAX(IF(`year` = 2016, view, NULL)) '2016'
    FROM    pub
    GROUP   BY url

Answer 3

you must make two table -> first to save files , second to save visits like this

Files Table

url_id | url
------------------------
1      |/document/item.pdf 
2      |/document/item.pdf 

Visits Table (url_id) is forign key from files table

url_id | time
---------------
1       | 987907872     
2       | 987907872
2       | 987978272
2       | 987907872
2       | 987907872
1       | 987907872
1       | 987907872
1       | 987907872

========================

then you can check time by year in visits table to view number of visits of each URL

Answer 4

May be it will help you

SELECT 
    url, 
    sum( if( year= '2014', view, 0 ) ) AS 2014,  
    sum( if( year= '2015', view, 0 ) ) AS 2015, 
    sum( if( year= '2016', view, 0 ) ) AS 2016 
FROM 
    pub
GROUP BY 
    url;