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mysqlsqldatabasejoinrdbms

MySql split an alias into multiple columns


select pd.products_name, 
GROUP_CONCAT(pag.customers_group_id SEPARATOR ',') group_id, 
pa.`options_values_price` Retail, 
GROUP_CONCAT(pag.options_values_price SEPARATOR ',') volume_and_designer


from products_attributes pa 

left join products_description pd 
on pa.products_id = pd.products_id and pd.language_id = '1' 

left join products_attributes_groups pag 
on pa.`products_attributes_id`= pag.`products_attributes_id`

where pa.products_id='225'

GROUP BY `pa`.`products_attributes_id` 

ORDER BY `pa`.`products_attributes_id` ASC

The above query return me an output like this

| products_name | group_id |   Retail |   volume_and_sdesign |
-------------------------------------------------------------
| GOLD          |    1,2   |  15      |       30,35          |
| SILVER        |    2,1   |  16      |       40,45          |
| BRONZE        |    1,2   |  17      |       50,55          |

what I want to achieve is add 2 more aliases in the table above so the last column (volume_and_sdesign) is separated into two columns (i.e volume, SDesign) according to group_id column. 1 corresponds to volume and 2 correspond to SDesign.

e.g

Gold has group_id (1,2)
so its volume_and_sdesign (30,35) will make new columns 
volume = 30
SDesign = 35

Silver has group_id (2,1)
so its volume_and_sdesign (40,45) will make new columns 
volume = 45
SDesign = 40

 Bronze has group_id (1,2)
so its volume_and_sdesign (50,55) will make new columns 
volume = 50
SDesign = 55

so, the above table will look like this

| products_name | group_id |   Retail |   volume_and_sdesign |  volume |  SDesign|
-------------------------------------------------------------
| GOLD          |    1,2   |  15      |       30,35          |30       | 35      |
| SILVER        |    2,1   |  16      |       40,45          |45       | 40      |
| BRONZE        |    1,2   |  17      |       50,55          |50       | 55      |

Any help will be much appreciated


Solution

  • You can use conditional aggregation -- that is case within an aggregation function such as max():

    select pd.products_name, 
           group_concat(pag.customers_group_id SEPARATOR ',') as group_id, 
           pa.`options_values_price` as  Retail, 
           group_concat(pag.options_values_price SEPARATOR ',') as volume_and_designer,
           max(case when group_id = 1 then pag.options_values_price end) as volume,
           max(case when group_id = 2 then pag.options_values_price end) as SDesign
    from products_attributes pa left join
         products_description pd 
         on pa.products_id = pd.products_id and pd.language_id = '1' left join
         products_attributes_groups pag 
         on pa.`products_attributes_id` = pag.`products_attributes_id`
    where pa.products_id='225'
    group by `pa`.`products_attributes_id` 
    order by `pa`.`products_attributes_id` ASC