db2 - How can I create a temporary numbers table with SQL? -


so came upon question asked list of unused account numbers. query wrote works, kind of hacky , relies on existence of table more records existing accounts:

with tmp      (select row_number()                   over(                     order cusno)            custtable          fetch first 999999 rows only) select tmp.a   tmp  not in (select cusno                    custtable)

this works because customer numbers reused , there more records unique customer numbers. but, said, feels hacky , i'd generate temporary table 1 column , x records numbered 1 through x. looked @ recursive solutions, of looked way more involved solution wound using. there easier way doesn't rely on existing tables?

i think simple answer no. able make determination of absence, platform needs know expected data set. can either generate temporary table or data set @ runtime - using method you've used (or variation thereof) - or can create reference table once, , compare against each time. i'd favour latter - table single column of integers won't put of dent in disk space , doesn't make sense compute identical result set on , on again.

here's article aaron bertrand deals issue:

https://sqlperformance.com/2013/01/t-sql-queries/generate-a-set-1

(edit: queries in article tsql specific, should adaptable db2 - , underlying analysis relevant regardless of platform)


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