Is this possible? (Desc. too long...)

joshmpratt

In PHP, I would like to be able to read data from a table, run a few If statements for each row and then write a value depending on the If statements outcome into one of the fields in that same row.

Is this possible, or is there a better way to do this?

TobyRT

Could you be a little more specific? it's possible, of course, if you know what you're looking for and how to write and if() statement!

joshmpratt

Sorry, it is somewhat difficult to explain... I know If statements just fine, my problem is figuring out a way to check through every row in a table, and write the timestamp date value that results in my set of it statements in a specific field of the row that I'm checking. Here's the code that I've written so far, and it's not working...

<?php
$db->query("SELECT * FROM gtraining WHERE start_date<NOW() AND end_date>NOW()");
while($db->fetch()) {
$thisid = $db->row['id'];
if ($db->row['date1'] > date('YmHis')) {
$nextdate = $db->row['date1'];
} else if ($db->row['date2'] > date('YmHis')) {
$nextdate = $db->row['date2'];
} else if ($db->row['date3'] > date('YmHis')) {
$nextdate = $db->row['date3'];
} else if ($db->row['date4'] > date('YmHis')) {
$nextdate = $db->row['date4'];
}
$query = "UPDATE gtraining SET next_date='$nextdate' WHERE id=$thisid";
}
?>

TobyRT

is this some kind of 'find next available date' script?

joshmpratt

Yes, essentially. There's 4 possible dates for each class. But I'm having the dates dissapear from being displayed if they are expired, and the whole class goes away completely when all 4 dates are expired. I need a way to sort the list though by the next available dates for the classes.

ahundiak

What exactly is not working? Echo out your update query statements and see if they look as you expect them to.

I'm guesing then when you actually execute your update statement, the results from your original query are being lost. You might need to store your update information in an array as you loop through your original query. And then do a second loop for the updates.

Or you might be able to do a $rows = $db->fetchAll() and then loop through $rows. Depends on how $db was designed.

joshmpratt

when I echo the $nextdate variable that I am having the loop store the next available date into, everything prints out as it should. The problem is that it is not writing anything into the database.

ahundiak

Well, clearly this:
$query = "UPDATE gtraining SET next_date='$nextdate' WHERE id=$thisid";

Needs to be followed with something like:
$db->execute($query);

To actually impact the database.

joshmpratt

Well I don't have a funciton called "execute" in the class that I'm calling the functions from. I'm working with a pre-made class, and I don't know what I would make the function "execute" do. Any idea what the execute function would look like?

joshmpratt

Holy crap... I think I just figured it out...

I added the code: mysql_query($query); after the UPDATE line.

And now it seems to be working... I need to change a bunch of dates around and test it for a while, but it appears to be working...

TobyRT

What's most disturbing is that I didn't notice the fact that you didn't actually run the query - you only defined it!

ahundiak

Glad to hear it's working. But you should look at the documentation for your $db class and see what the right way to execute an update statement is. You really don't want to mix $db with mysql_statements.

joshmpratt

well, I probably don't need to use the class that I'm having the $db use. I'm only doing that because the guy who was webmaster before me used that in all his stuff. How would I write the code without using the class?

ahundiak

The manual http://www.php.net/manual/en/ref.mysql.php is often a good starting point.

But learning how to use $db would probably be better in the long run.