[Resolved] simple mysql update DB..well for some

azunoman

Ok..I can add lots of stuff to my DB....it cool...but now I am ready for updating, via admin panels I have created. So here goes the ?.

If one has a table with 30 fields, and they can update one or more of these fields, and I code my update routine with all the fields, thus resulting in some fields being passed as null. What happens with the update, specifically the columns that will be passed null data but already contain data?

Is this where the table null/no null col definitions come in?...

Best Regards
Vincent

www.diggingditches.com

mmilano

mysql_query("insert into table set field1='1',field2='2',field3='3'");

mysql_query("update table set field1='1',field2='',field3='a'");

the second query would replace field to to ''

if you had null constraints in mysql, then mysql would throw an error.

if you did not want to modify field2, then you would exclude that from the update:

mysql_query("update table set field1='1',field3='a'");

hope this answered the ?

azunoman

Thanks...this proves what I thought originally and hoped to glean from others experience and bypass the experiment.

The reason for the initial question was because I use alot of variable variable's and in this particular form (using $_POST doesn't work). I display the exiting DB results, i.e. first name etc, in a seperate table column, and an input field next to in in another column, so it was very possible that the input field would be null.

I have now reverted this to display and allow the input from same text box, hence I will have values for a complete update.

     //assume &i=1-n             $temp ="username$i"; $usernamev = $$temp;    <input name="<?php echo "username$i";?>" value="<?php if (empty($usernamev)) $usernamev=$thisuser['username']; echo $usernamev;?>" type="text" size="25" maxlength="25">

I really like php, my background is mainframe assembler, so I get myself into trouble by really complicating things...but when finished with this website, it going to ROCK!

Cheers,

Vincent
www.diggingditches.com

philipolson

Why not instead use an array? It's much preferred to use arrays than variable variables all over the place. Have a look:

http://www.php.net/manual/en/faq.html.php#faq.html.arrays
http://www.php.net/manual/en/language.variables.external.php

azunoman

Uhm..arrrays...haven't actually got a handle on them yet. Yes, I wonder wether or not variable variables are the right choice, especially since they sometimes drive me crazy.

The main reason I use them is that I don't like static forms. For example, when adding/displaying columns to/in a database, like a personal information, I allow for the user to click on 'more' to get additional form space/display all detail. I have found that variable variables work nicely for this. And with using dynamic forms, I found that $POST does not work, unless I suppose I used $POST['array'].

I am still floundering on finding best practice for myself. Arrays are still somewhat esoteric for me. But one would think that if I can code variable variables in complex forms, then I could understand the use of arrays, time will get me there. I also don't have a handle on classes and have this feeling that I can speed up my development using them.

I have been using php for about 3 months now. I am building a rather large and complex site and find myself say on page 16, learning things and going back and applying those learnings to pages 1-15...argh...it grunt work...

Many thanks to the user community for some of the arcane ?'
s that I have posed. Also I feel that the answers/directions here are of better quality than those on phpfreaks.

philipolson

Arrays are ideal for your task, trust me on this one! I don't think you should continue on to page 17 until you successfully create/parse a form using arrays. ;-)

Not sure what you mean by saying "cannot use $POST" as you've said that twice now. If the information comes from POST you can (and should) use $POST. Using your variable variable example: echo $POST["username$i"]; or an array: echo $POST['username'][$i];

Example reasons why arrays are cooler (in this case):

Look how easy it is to add username form elements, always the same, no variable variable garbage to worry about. Let's say you wanted to see how many usernames were entered: echo count($_POST['username']); Yes, it's that easy.

azunoman

"Can't use $_POST", didn't mean that it couldn't be used, but that I don't know how.

Rather than go to page nth, I have been coding a test page...I have just backed them up and now am going to try the $_POST methods you described.

??? Are variable variables, just not a good choice...in your example I could use them and not have to code the [$]. But then I have to carry the vv's around from main page to processing page.

Thanks for holding my hand to this point, but don't let go yet!...I will report back soon.

Vincent