Get max number from table add one and check with specific convention - sql

Question

I have to produce artikel number based on some convention, and this convention is as below
The number of digits
{1 or 2 or 3}.{4 or 5}.{n}
example products numbers:
7.1001.1
1.1453.1
3.5436.1
12.7839.1
12.3232.1
13.7676.1
3.34565.1
12.56433.1
247.23413.1
The first part is based on producent, and every producent has its own number. Let's say Rebook - 12, Nike - 256 and Umbro - 3.
I have to pass this number and check in table if there are some rows containing it e.g i pass 12 then i should get everything which starts from 12.
and now there should be three cases what to do:
1st CASE: no rows at the table:
then retrieve 1001
2nd case: if there are rows
so for sure there is already at least one:
12.1001.1
and more if they are let's say:
12.1002.1
12.1003.1
...
12.4345.1
so should be retreived next one so: 4346
and if there are already 5-digits for this product so let's say:
12.1002.1
12.1003.1
...
12.9999.1
so should be retreived next one so: 10001
3rd case: in fact same as 2nd but if it rached 9999 for second part:
12.1001.1
...
12.9999.1
then returned should be: 10001
or
12.1002.1
12.1003.1
...
12.9999.1
12.10001.1
12.10002.1
so should be retreived next one so: 10003
Hope you know what i mean
I already have started something. This code is taking producent number - looking for all rows starting with it and then just simply adding 1 to the second part unfortunetly i am not sure how should i change it according to those 3 cases.
select
parsename(max(nummer), 3) + '.' -- 3
+ ltrim(max(cast(parsename(nummer, 2) as int) +1)) -- 5436 -> 5437
+ '.1'
from tbArtikel
where Nummer LIKE '3.%'
Counting on your help. If something unclear let me know.
Additional question:
Using cmd As New SqlCommand("SELECT CASE WHEN r.number Is NULL THEN 1001
WHEN r.number = 9999 THEN 10001
Else r.number + 1 End number
FROM (VALUES(#producentNumber)) AS a(art) -- this will search this number within inner query And make case..
LEFT JOIN(
-- Get producent (in Like) number And max number Of it (without Like it Get all producent numbers And their max number out Of all
SELECT PARSENAME(Nummer, 3) art,
MAX(CAST(PARSENAME(Nummer, 2) AS INT)) number
FROM tbArtikel WHERE Nummer Like '#producentNumber' + '[.]%'
GROUP BY PARSENAME(Nummer, 3)
) r
On r.art = a.art", con)
cmd.CommandType = CommandType.Text
cmd.Parameters.AddWithValue("#producentNumber", producentNumber)

Answer 1

A fairly straight forward way is to (ab)use PARSENAME to split the string to be able to extract the current maximum. An outer query can then just implement the rules for the value being missing/9999/other.
The value (12 here) is inserted in a table value constructor to be able to detect a missing value using a LEFT JOIN.
SELECT CASE WHEN r.number IS NULL THEN 1001
WHEN r.number = 9999 THEN 10001
ELSE r.number + 1 END number
FROM ( VALUES(12) ) AS a(category)
LEFT JOIN (
SELECT PARSENAME(prodno, 3) category,
MAX(CAST(PARSENAME(prodno, 2) AS INT)) number
FROM products
GROUP BY PARSENAME(prodno, 3)
) r
ON r.category = a.category;
An SQLfiddle to test with.
As a further optimization, you could add a WHERE prodno LIKE '12[.]%' in the inner query to not parse through un-necessary rows.

Answer 2

I don't fully understand what you're asking for. I am unsure about the examples...but if i was doing it I'd try to break the field into 3 fields first and then do something with them.
sqlfiddle
SELECT nummer,LEFT(nummer,first-1) as field1,
RIGHT(LEFT(nummer,second-1),second-first-1) as field2,
RIGHT(nummer,LEN(nummer)-second) as field3
FROM
(SELECT nummer,
CHARINDEX('.',nummer) as first,
CHARINDEX('.',nummer,CHARINDEX('.',nummer)+1)as second
from tbArtikel)T
Hopefully with the 3 fields broken up, it's much easier to apply logics to them now.
update:
Okay i reread your question and i sort of know what you're trying to get at..
if user search for a value that doesn't exist for example 8.
Then you want 1001 returned
if they search for anything else that has results then return the max+1
unless it's 9999 then return 10001.
If this is correct then check this sqlfiddle2
DECLARE #search varchar(20)
SET #search = '8'
SELECT field1,max(nextvalue) as nextvalue FROM
(SELECT field1,
MAX(CASE (field2)
WHEN 9999 THEN 10001
ELSE field2+1
END) as nextvalue
FROM
(SELECT nummer,
CAST(LEFT(nummer,first-1) as INTEGER) as field1,
CAST(RIGHT(LEFT(nummer,second-1),second-first-1) as INTEGER) as field2,
CAST(RIGHT(nummer,LEN(nummer)-second) as INTEGER) as field3
FROM
(SELECT nummer,
CHARINDEX('.',nummer) as first,
CHARINDEX('.',nummer,CHARINDEX('.',nummer)+1)as second
FROM tbArtikel
)T
)T2
GROUP BY field1
UNION
SELECT CAST (#search as INTEGER)as field1 ,1001
)T3
WHERE field1 = #search
GROUP BY field1
Just change the #search variable to see it's results
I think there might be a cleaner way to do this but it's not coming to me right now :(

Answer 3

If you really can't add 2 new fields (is't probably the simplest and fastest solution), and probably can't add functional index, you must extract 2nd part number and get max of this, increment, then concatenate with your condition 1st part number and '.1' at the end:
SELECT :par1 || '.' || (Max(To_Number(SubStr(nummer, dot1 + 1, dot2 - dot1 -1 ))) + 1) || '.1' NEW_number
--SELECT SubStr(nummer, 1, dot1 - 1) N1st, SubStr(nummer, dot1 + 1, dot2 - dot1 -1 ) N2nd, SubStr(nummer, dot2 + 1) N1th
FROM (
SELECT nummer, InStr(nummer, '.') dot1, InStr(nummer, '.', 1, 2) dot2
FROM tbArtikel
WHERE nummer LIKE :par1 || '.%')
;
--GROUP BY SubStr(nummer, 1, dot1 – 1)
it was for oracle sql, i don't have sql-serwer to test, but probably this is simplest answer:
select #par1 + '.' + (select max(cast(SUBSTRING(nummer, CHARINDEX( '.', nummer, 1 ) +1, CHARINDEX( '.', nummer, CHARINDEX( '.', nummer, 1 ) +1 ) - CHARINDEX( '.', nummer, 1 ) -1) as int)) + 1 from tbArtikel where nummer LIKE #par1 || '.%') + '.1'
if parsename(nummer, 2) is you defined function to get 2nd number then:
select #parm + '.' + (max(cast(parsename(nummer, 2) as int)) + 1) + '.1'
from tbArtikel
where Nummer LIKE #parm + '.%'