make the price of one line the price of all lines - mysql

Question

I just started using mysql for SAP.
I would like to get this result:
DocEntry Description Price
00001 item A 100.00
00003 item C 110.00
From this data
DocEntry Description Quantity Price
00001 item A 2 300.00
00001 freight - 100.00
00002 item A 1 300.00
00003 item C 1 300.00
00003 freight - 110.00
I tried to filter the items with freight through this:
create view table_a
as
select DocEntry, Description, Price
from inv1 where Description like 'freight'
create view table_b
as
select DocEntry, Description, Price
from inv1
where exist (select * from table_a where table_a.DocEntry = table_b.DocEntry
I don't know though what to do with price?
Thanks!

Answer 1

It looks like you want the freight fit each item:
select distinct a.DocEntry, a.Description, b.Price
from inv1 a
join inv1 b on a.DocEntry = b.DocEntry
where a.Description != 'freight'
and b.Description = 'freight'
although the data does not require it, the distinct keyword has been added in case there are multiple "item" rows for each "freight" row. If the is no possibility of that ever happening, distinct may be removed.

Answer 2

It's not quite clear what you're asking, but maybe something like this...
DROP TABLE IF EXISTS my_table;
CREATE TABLE my_table
(DocEntry INT NOT NULL, Description VARCHAR(12) NOT NULL, Quantity INT NULL,Price INT NOT NULL,PRIMARY KEY(DocEntry,Description));
INSERT INTO my_table VALUES
(1,'item A',2,300),
(1,'freight',NULL,100),
(2,'item A',1,300),
(3,'item C',1,300),
(3,'freight',NULL,110);
mysql> SELECT * FROM my_table;
+----------+-------------+----------+-------+
| DocEntry | Description | Quantity | Price |
+----------+-------------+----------+-------+
| 1 | freight | NULL | 100 |
| 1 | item A | 2 | 300 |
| 2 | item A | 1 | 300 |
| 3 | freight | NULL | 110 |
| 3 | item C | 1 | 300 |
+----------+-------------+----------+-------+
SELECT docentry
, MAX(CASE WHEN description = 'freight' THEN price END) price
, MAX(CASE WHEN quantity IS NOT NULL THEN description END) description
FROM my_table
GROUP
BY docentry
HAVING price IS NOT NULL;
+----------+-------+-------------+
| docentry | price | description |
+----------+-------+-------------+
| 1 | 100 | item A |
| 3 | 110 | item C |
+----------+-------+-------------+