Re: [PHP] Getting my head around nulls
Steve Cayford [EMAIL PROTECTED] on 25/09/2001 17:28:57 To: [EMAIL PROTECTED] cc: [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: Re: [PHP] Getting my head around nulls On Tuesday, September 25, 2001, at 10:30 AM, [EMAIL PROTECTED] wrote: Just had a look at manual, ifnull() seems close to useless. However if they had NVL(), as Oracle douse NVL( column|litrel, '*null*' ) This takes a column or literal as its first arg and if arg is null returns 2nd arg otherwise returns arg. In other words if the column is null it is replaces by arg2 otherwise it is simply returned. Um, that's what ifnull() does. At least it works for me. -Steve Verry true, sorry, was looking at nullif. Also noticed the if function, can this have more than three parameters. i.e if ( col, 'A', 'Accept', 'C', 'Complete', 'Unknown' ) like Oracle decode. and if elseif else structure. Neb -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
Re: [PHP] Getting my head around nulls
On Wednesday, September 26, 2001, at 02:48 AM, [EMAIL PROTECTED] wrote: Steve Cayford [EMAIL PROTECTED] on 25/09/2001 17:28:57 To: [EMAIL PROTECTED] cc: [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: Re: [PHP] Getting my head around nulls On Tuesday, September 25, 2001, at 10:30 AM, [EMAIL PROTECTED] wrote: Just had a look at manual, ifnull() seems close to useless. However if they had NVL(), as Oracle douse NVL( column|litrel, '*null*' ) This takes a column or literal as its first arg and if arg is null returns 2nd arg otherwise returns arg. In other words if the column is null it is replaces by arg2 otherwise it is simply returned. Um, that's what ifnull() does. At least it works for me. -Steve Verry true, sorry, was looking at nullif. Also noticed the if function, can this have more than three parameters. i.e if ( col, 'A', 'Accept', 'C', 'Complete', 'Unknown' ) like Oracle decode. and if elseif else structure. Neb Looks like you want the CASE statement. I haven't used it but it looks pretty much like what you're asking. CASE value WHEN [compare-value] THEN result [WHEN [compare-value] THEN result ...] [ELSE result] END Guess this discussion should really be on php-db :) -Steve -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
RE: [PHP] Getting my head around nulls.
I wish the rest of the world saw it that way! But not so... That's what capitalism does for you -;) You may want to look at MySQL's IS_NULL function for retrieving data. Other than that, I don't have any good advice. It seems that if you retrieve a NULL from the database and try to assign it to a PHP variable, that variable gets destroyed. AFAIK, yes, you need a bunch of data checks, both putting data in and pulling it back out. Strange, I did a search on is_null in the MySQL manual (ver 3.23.40 .pdf) and got no nits on is_null. Could you provide example of its use. Neb -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
Re: [PHP] Getting my head around nulls.
SELECT * from some_table WHERE some_field IS NULL; Andrey Hristov IcyGEN Corporation http://www.icygen.com BALANCED SOLUTIONS - Original Message - From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Sent: Tuesday, September 25, 2001 4:09 PM Subject: RE: [PHP] Getting my head around nulls. I wish the rest of the world saw it that way! But not so... That's what capitalism does for you -;) You may want to look at MySQL's IS_NULL function for retrieving data. Other than that, I don't have any good advice. It seems that if you retrieve a NULL from the database and try to assign it to a PHP variable, that variable gets destroyed. AFAIK, yes, you need a bunch of data checks, both putting data in and pulling it back out. Strange, I did a search on is_null in the MySQL manual (ver 3.23.40 .pdf) and got no nits on is_null. Could you provide example of its use. Neb -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED] -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
RE: [PHP] Getting my head around nulls.
SELECT * from some_table WHERE some_field IS NULL; Andrey Hristov -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED] Thanks for correcting my misspelling, Andrey, IS NULL not IS_NULL. Another thing to look at, Ben, is IFNULL(). I would give you an example, but I never got it to work like I thought it should ;) I think it is supposed to return an alternate value for NULLs. Kirk -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
RE: [PHP] Getting my head around nulls.
Just realised, you meant 'is null' not is_null. Sorry, couldn't see the wood for the trees. This in ANSI SQL and I use it every day. Had a look at zootweb.com. And I thought ASP meant 'Active Server Pages' not 'Application Service Provider'. And not a zoot suit in sight -;) Regards, Neb -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
RE: [PHP] Getting my head around nulls
Thanks for correcting my misspelling, Andrey, IS NULL not IS_NULL. Another thing to look at, Ben, is IFNULL(). I would give you an example, but I never got it to work like I thought it should ;) I think it is supposed to return an alternate value for NULLs. Just had a look at manual, ifnull() seems close to useless. However if they had NVL(), as Oracle douse NVL( column|litrel, '*null*' ) This takes a column or literal as its first arg and if arg is null returns 2nd arg otherwise returns arg. In other words if the column is null it is replaces by arg2 otherwise it is simply returned. Next week I will sing the prases of the oracle decode statement -;) The week after that I will get all exited about MySQL freetext indexes, yum, yum. Neb -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
Re: [PHP] Getting my head around nulls
On Tuesday, September 25, 2001, at 10:30 AM, [EMAIL PROTECTED] wrote: Thanks for correcting my misspelling, Andrey, IS NULL not IS_NULL. Another thing to look at, Ben, is IFNULL(). I would give you an example, but I never got it to work like I thought it should ;) I think it is supposed to return an alternate value for NULLs. Just had a look at manual, ifnull() seems close to useless. However if they had NVL(), as Oracle douse NVL( column|litrel, '*null*' ) This takes a column or literal as its first arg and if arg is null returns 2nd arg otherwise returns arg. In other words if the column is null it is replaces by arg2 otherwise it is simply returned. Um, that's what ifnull() does. At least it works for me. -Steve Next week I will sing the prases of the oracle decode statement -;) The week after that I will get all exited about MySQL freetext indexes, yum, yum. Neb -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED] -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
RE: [PHP] Getting my head around nulls.
And remember 0 as a number is as important as any other number. I wish the rest of the world saw it that way! But not so... You may want to look at MySQL's IS_NULL function for retrieving data. Other than that, I don't have any good advice. It seems that if you retrieve a NULL from the database and try to assign it to a PHP variable, that variable gets destroyed. AFAIK, yes, you need a bunch of data checks, both putting data in and pulling it back out. Kirk -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Monday, September 24, 2001 8:59 AM To: [EMAIL PROTECTED] Subject: [PHP] Getting my head around nulls. First recap (been doing RDBMS stuff for over 10 years so reckon this is correct). Nulls and blank are NOT the same in RDBMS (in fact there are actually several types of nulls). MySQL implements this correctly (Unlike Oracle which treats null and blank the same). Up to now I am OK but when it comes to codeing in PHP I am not to sure about best practice. The app I am working on for number datatypes inserts 0 if no data is entered in form. I can see why, I am inserting a blank into the database and MySQL goes (Hang on this is a number fields and as you are not inserting NULL you obviously mean zero). So I guess I need to do some conditional stuff so the blanks are not actually inserted or put null into the PHP variable and insert this (Can PHP vars be null but exist?). Or is their another option? The second half of the issue is getting data from the database. I added a couple of columns to database but then I tried to retrieve them as $row[index]. I got a variable x douse not exist error. This really through me until I realised it was because the value in the database was null and it kind of makes sense not to create the var for nulls (although it makes coding a pig). So again, it seems I need to do a lot of isset() stuff which is going to be a pain. Any other insight. Nulls with varchar/char types are not so much of a problem as long as you don't mind all fields in the database being blank rather than null after you first insert data into them. It would be good to get peoples advice on this. And remember 0 as a number is as important as any other number. -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
