MySQL how to calculate after stock taking - mysql

Question

Data tables in the following manner;
Firm | PartID | StockCount | Date | Type
-----------------------------------------------------------
1 | 71 | 5 | 2014-02-01 | Incoming Invoice
1 | 71 | -1 | 2014-02-09 | Send Invoice
1 | 71 | 10 | 2014-02-13 | Stocktaking ( !!! Of the Depot. )
1 | 71 | -1 | 2014-02-21 | Send Invoice
1 | 71 | 5 | 2014-02-28 | Incoming Invoice
This table is actually a stock is a fictionalized depiction of movement table. Counts in this table made ​​in the store, purchase and sales invoices include. In this way, entering the warehouse, from the warehouse and the warehouse will be collected in a table quantities actually counted. From the moment that made ​​the Census, stock values ​​should be calculated over the stated amount. Where the problem was coming.
How do I get the following result?
Firm | PartID | StockCount | Date | Type
-------------------------------------------------------
1 | 71 | 14 | NULL | NULL

Answer 1

You seem to want the sum of the stock after "stock taking", which I suspect is more normally called "doing inventory" in English.
select Firm, PartId, sum(StockCount) as StockCount, NULL as Date, NULL as Type
from table t
where Date >= (select max(Date)
from table t2
where t2.Firm = t.Firm and
t2.partid = t.partid and
t2.type = 'Stocktaking'
)
group by Firm, Partid;
If there may be no Stocktaking record, then go with a left join approach:
select Firm, PartId, sum(StockCount) as StockCount, NULL as Date, NULL as Type
from table t left join
(select Firm, PartId, max(Date) as maxDate
from table t
where t2.type = 'Stocktaking'
group by Firm, PartId
) as tfp
on t.Firm = tfp.Firm and t.PartId = tfp.PartId and t.Date >= tfp.MaxDate
group by t.Firm, t.PartId;

Answer 2

If I am reading it right:
SELECT firm, partid, count(stockCount) as stock_total
FROM yourtable
WHERE firm = 1
AND partid = 71
You'll need to group by if you want to select multiple parts, something like:
SELECT firm, partid, count(stockCount) as stock_total
FROM yourtable
WHERE firm = 1
GROUP BY partid

Answer 3

Try this
SELECT Firm,
PartID,
Count(StockCount),
Date AS NULL,
TYPE AS NULL
FROM TABLE
GROUP BY Firm,
PartID

Answer 4

Your explanation of the problem is unclear, but I assume it is what you want.
SELECT Firm, PartID, SUM(StockCount) as StockCount, NULL as Date, NULL as Type
FROM tbl T1
WHERE Date >= (SELECT Date FROM tbl T2
WHERE T2.Type = Stocktaking
AND T1.Firm =T2.Firm
AND T1.PartId = T2.PartId
)
GROUP BY Firm, PartID