如何在一条记录中获取不同记录的两个字段 Mysql

Question

I have one table with this content(There are more fields that are not relevant):

A transaction can be purchase or sale. A purchase can be id_factura or id_albaran, if it's purchase id_factura, id_albaran is Null and vice versa, the sale is the same. But a sale can have two records with the same imei, as we see in the example: id_purchasesale 2 and 3 (in this case it will always have the same price, in example 250).

The imei field can only exist as a purchase once (invoice_id or albaran_id) and as a sale once or twice.

If there is a purchase and there is no sale of the same imei you don't have to show it.

TABLE purchasesale

id_purchasesale    transaction    id_factura    id_albaran    Model      imei     price
  1                purchase         1            Null       Samsung      30888     200 
  2                sale             1            Null       Samsung      30888     250
  3                sale             Null         1          Samsung      30888     250  
  4                purchase         Null         1          Apple        52101     300
  5                sale             1            Null       Apple        52101     380  
  6                purchase         2            Null       Motorola     77520     300
  7                sale             2            Null       Motorola     77520     350
  8                purchase         3            Null       Xiaomi       29102     150

What I want to obtain is the following result, a field with the purchase price, another field with the sale price and another field with the profit of these two fields and the model field.

imei        price_purchase    price_sale   profit   Model 
30888            200             250        50      Samsung
52101            300             380        80      Apple
77520            300             350        50      Xiaomi

Answer 1

You can try below -

select imeid,
       max(case when transaction='purchase' then price else 0 end) as purchase_price,
       max(case when transaction='sale' then price else 0 end) as sale_price,
       max(case when transaction='sale' then price else 0 end)-max(case when transaction='purchase' then price else 0 end) as profit,
       model
from tablename
where transaction in ('purchase','sale')
group by imeid,model
having count(distinct transaction)=2

Answer 2

you sould use the same table two using alias and filtering by sale and purchase

select  a.imei
 , a.model
 , a.price as  price_purchase
 , b.price as price_sale
 , b.price - a.price  as profit
from  purchasesale a 
inner join  purchasesale b  on a.imei = b.imei 
    and a.transaction ='purchase'  
      and b.transaction ='sale' 

Answer 3

Your table design is a mess. If you can change it I would split this table in three separate tables, one for purchases, one for sales, and one for phones.

However, with the current situation, this should do what you require:

SELECT
 t1.imei as imei,
 t1.price as price_purchase,
 t2.price as price_sale,
 (t2.price - t1.price) as profit,
 t1.model as model
FROM purchasesale t1, purchasesale t2
WHERE t1.imei = t2.imei and
 t1.transaction = 'purchase' and
 t2.transaction = 'sale'

Hope I helped!