Need a loop

Question

What kind of loop syntax can be added to...
SELECT TRUNC(SYSDATE) dt FROM dual
... such that it returns all dates between 3/1/2007 and SYSDATE?

Answer 1

well, perhaps Tom was trying to "dumb it down" for other people. I really find it hard to accept that Tom believes in magic in an oracle database. Perhaps Tom was busy those days, and had ghost writers?
I don't see the humor in dual that Jonathan does, howver I will agree that it is "special" and an "irritant". special in that you assume there is only one row, and as such, can write code to rely on that, and you ignore the "full" scans in explain plans. An irritant in that you assume it has one row, and then some knucklehead runs a catalog script by mistake, adding a second row to it, and things no longer work as expected; plus some blowhard is always complaining about the full scan from dual.
Chuck? Hmmm, well, he's a special, magical case, isn't he. I'd give more credence to that quote if I could find it published by oracle (instead of on random blogs and forums). But, for the sake of argument, I'll assume it's true (but if you have a link to it from oracle, I would appreciate it). Regardless of his intentions, the table has existed as a normal, regular, accessible table since at least v5 (that's when I started using oracle, and dual was there then). and even today, in my 10g database, dual is no different than any other table - just check dba_tables.
the only distinction to be made is the distinction between data, not tables. if you know that a table has one row, you can use it without worrying about extra where, connect by, or group clauses. dual works the same as any other table:
select dummy, level
from dual
connect by level < 5
and prior dummy=dummy
and prior dbms_random.value is not null;
D      LEVEL
X          1
X          2
X          3
X          4so, the solution that I gave (the one that nobody ever asked for, even though it was the one they wanted all along) works the same for DUAL and for EMPLOYEE. but since the DATA in dual is different than the DATA in employee, you can write a shorter statement when using dual. is that really magic? no, it's just the laws and rules of sql.
and I never accused the OP of saying dual is "imaginary" (although I chuckled when I read it from you). I'm simply trying to straighten him out, and get him to understand that dual is no different than any other table with one column and one row. that's for his benefit going forward. he'll write much better code if he actually understands what he's doing.
and the OP did make a blanket statement that "connect by level" does not work on other tables. but it does. like everything in oracle, it just needs to be done correctly. however, I give the OP credit for retracting his statement after he was corrected - "without sufficient syntax to avoid what happened". as I stated, because the data in dual is different than the data in other tables, the "sufficient" sql is different.
defensive, no. just stating the facts for the edification of the OP, and anyone else reading this thread.
rude, maybe. depends on how overly sensitive you are.