On 9/13/06,
Brandon Aiken <
BAiken@winemantech.com> wrote:
I think I mistakenly sent this to General instead of Novice. Oops.
Oh well. I posted back to Novice.
Yeah, I either skipped over or forgot the bit in the OP about bools. Mea culpa.
Hehe.
You should be able to use OR instead of AND in any logical expression.
Well this sounds more like what I want. Given t2.fielda, t2.fieldb, t2.fieldc, any one (or all three) could be true, but frequently at least one of the fields is false. Initially, all of the fields might be unknown (thus NULL) for a given item until I am able to investigate the items to determine TRUE/FALSE. I frequently have items that are inactive, and thus unable to determine any of attributes in t2.
My end result needs to be a count of all the values in each field where the value is TRUE, as opposed to FALSE or NULL.
Yeah, I would probably run 4 separate, simple queries. That will get you the best performance since you're doing no JOINs and no composite queries.
There are actually 12 fields involved. I figured if I could just learn how to handle the first few, I could probably take it from there.
If you need to enter the results into another table, try INSERT … to insert the defaults and any primary key you have (like timestamp), then four UPDATE … SELECT statements.
Cool. I'll play around with it a while, see what I come up with.
The real problem with NULLs is some of the (in my mind) nonsensical results you get, especially with logical operators:
NULL AND TRUE => NULL
NULL OR TRUE => TRUE
NULL AND FALSE => FALSE
NULL OR FALSE => NULL
Plus you have to use IS instead of = since any NULL in an = expression makes the result NULL (yes, this is an error in my previous queries). NULL just has all these special cases. I find it much nicer to avoid it wherever possible since it has somewhat unpredictable results.
Wow. Guess that could give me some interesting results, depending on what I do! Thanks again for the input.
Don
