Problem to calculate values from 1 table using group by in firebird - sql

Question

I have a logic problem to calculate the final value of this table:
https://i.stack.imgur.com/YPXXX.png
I need calculate for every row with column TIPO having the value "E" +1 and for "S" -1, grouping by columns Codigo and Configuracao.
Basically, I need a simple stock control, the columns Codigo and Configuracao is product column control, and TIPO is the type of moviment, S = OUT and E = IN
Anyone can give me a light?

Answer 1

untested but maybe this
select SUM(t1.TipoNumeric), t1.CODIGO, t1.CONFIGURACAO from (
select
case (TIPO)
when 'E' then 1
when 'S' then -1
else 0
end as TipoNumeric,
CODIGO,
CONFIGURACAO
from MyTable
) as t1
group by t1.CODIGO, t1.CONFIGURACAO

Answer 2

Just add that +1/-1 column, perhaps?
alter table MyTable
add tipo_val computed by
(
decode( upper(TIPO), 'E', +1, 'S', -1 )
)
https://firebirdsql.org/file/documentation/html/en/refdocs/fblangref25/firebird-25-language-reference.html#fblangref25-ddl-tbl
https://www.firebirdsql.org/refdocs/langrefupd21-intfunc-decode.html
And then:
Select * from MyTable;
Select SUM(tipo_val), CODIGO, CONFIGURACAO
From MyTable
Group by 2, 3
P.S. do not use pictures to show your data.
Instead put them to http://dbfiddle.uk/?rdbms=firebird_3.0 as a script,
and then use Markdown Export there to copy both data and a hyperlink into your question text.
P.P.S. i believe your whole approach is wrong there, if "need a simple stock control".
https://en.wikipedia.org/wiki/Double-entry_bookkeeping
https://medium.com/#RobertKhou/double-entry-accounting-in-a-relational-database-2b7838a5d7f8
I think your table should have columns like that:
surrogate row id, primary key, auto-incrementing integer, 32-bits or 64-bits
columns identifying your item, usually it is, again, a single surrogain integer SKU (Stock Keeping Unit) referencing (see - Foreign Keys) another "dictionary table". In your case it seemes to be two columns Codigo and Configuracao but that also means you can not add extra information ("attributes") about your items, like price or photo (read: database normalization). It also makes grouping harder for Firebird Engine, than using a single integer column. Also, you did created an index on the item-identifying column(s) did you not? What is your query plan on those selects, do they use index on Codigo and Configuracao or an ad hoc external sorting instead?
the timestamp of an operation, that is automatically set by the Firebird server to be current_timestamp, so you always know when exactly that row was inserted. Indexed, of course.
the computer user who added that row, again, automatically set by Firebird server to current_user or to an ID of a user in some stock_workers table you would create. Surely, indexed too.
some description of an operation, like contract number, or seller name, anything that would help you later to remember what real world event that row even describes. Being free form text, it probable would not be indexed. But maybe you would eventually make some contracts or sellers table and add integer references (FK IDs) to those tables? That depends which exactly kind of data would be repeated often enough to be worth extracting into an extra indexed columns.
maybe a unit measure, maybe all your units forever would only be measured in pieces, in integer quantity. But maybe there would be some items measured in kilograms, meters, liters, etc?
finaly two integer (or float?) columns like Qty_Income and Qty_Outcome, where you would record how many items were added or taken from your depot. There would be not that E/S column! There would be two integer columns, that you would put number into one or another. Why? read the articles about bookkeeping above!
In such a database scheme your query would finally look like this:
select Sum(s.Qty_Income) as Credit, Sum(s.Qty_Outcome) as Debit,
Sum(s.Qty_Income) - Sum(s.Qty_Outcome) as Saldo,
min(g.Codigo), min(g.Configuracao)
from stock_movements s
join known_goods g on g.ID = s.SKU_ID
group by s.SKU_ID
And you would also be able to flexibly compose similar requests grouping by workers, or dates, or quantities (like, only care about BIG events like 1000 or more items added in one operation), or anything.