I use this code to output all threads with a specific forum ID
$query = mysql_query("SELECT * FROM forums JOIN threads ON threads.fid = forums.id WHERE forums.id = ".intval($_GET['forumID']));
$forum = mysql_fetch_assoc($query);
?>
<h1><a>Forums</a> > <?=$forum['name']?></h1>
<?php while ($thread = mysql_fetch_array($query)): ?>
<?=$thread['title']?>
<?php endwhile; ?>
forums
id, name, description
threads
id, title, message, fid
Thing is that it outputs all threads exept one. If I remove one it just hides another. Why is that?
Would really appreciate some help!
sorry my english is not that good, lets say i have 4 records in threads with fid = (in this case 1), it only outputs 3 of them
You are using the first row returned in the mysql_fetch_assoc in line 2. In your while loop condition, the mysql_fetch_array function will starts with the second row of the sql query, not the first. Therefore, the id from the first row is missing in your list. However, if you use the column name, you should also use mysql_fetch_assoc, not mysql_fetch_array. This should not give you any ids.
The reason you have one fewer threads than you're expecting is that you're fetching the first thread in line 2, but only using it to display the forum name. You then fetch the second row in the while loop and start from there to list the threads - missing the first row.
I'd refactor your code using the do..while control structure in PHP, as follows:
$query = mysql_query("SELECT * FROM forums JOIN threads ON threads.fid = forums.id WHERE forums.id = ".intval($_GET['forumID']));
$thread = mysql_fetch_assoc($query);
if ($thread != null) {
echo "<h1><a>Forums</a> > $thread['name'] </h1>";
do {
echo $thread['title'];
} while ( $thread = mysql_fetch_array($query)) );
}
As txwikinger pointed out, the internal array pointer is moved forward by mysql_fetch_assoc(), so the first time you use mysql_fetch_array(), you'll get the second row. You can reset the array pointer with mysql_data_seek() before using the array a second time.
mysql_data_seek($query, 0);
I'd rather restructure the code to use two queries though, one to get the forum name in one tiny query, and one to get all the threads in another query.
Related
<?php
$connect = mysqli_connect("localhost", "root", "", "hempbag_db") or die("Connection failed");
$query= "Select * from tbl_sales";
$ress = mysqli_query($connect, $query);
$result = mysqli_fetch_array($ress);
foreach($result as $a)
{
echo $a['ID']; // This doesnt print although i used fetch array
}
foreach($ress as $a)
{
echo $a['ID']; // This works why???? This variable has only query run
}
?>
Why does the upper foreach does not run and lower one does? Can anyone explain please?
When you run a query, it returns a result:
$ress = mysqli_query($connect, $query);
var_dump($ress); // You will see it's a result.
At this point $ress just contains the result of what you just queried. Think of it like this:
You goto the warehouse, and you make and order for 1000 boxes of crackers. She heads to the back, and gets your boxes ready, and comes back and hands you a piece of paper with the order number. (This is $ress). Now, you can't loop through that, you can't do anything with that.
You now take that piece of paper, and you hand it to your assistant, and you say you want to get all the crackers on your trucks (This is now mysqli_fetch_array()). Your assistant goes, fetches it, and returns you the crackers.
Simply put, mysqli_query just returns an object like Result#1. From Result#1, mysql can tell you how many rows were returned mysql_num_rows(Result#1), or get actual data if it was a select query: mysqli_fetch_array(Result#1).
Now onto the reasoning: Performance. Let's say you didn't want 1000 crackers, you just wanted to know if they had 1000 crackers. If she came back with all the boxes of crackers and you had to count them yourself, it would be much more difficult. Instead, with that piece of paper, she can determine how many boxes you were able to order. Less data being transferred, and much more efficient.
Just a small note, in later versions of php, they made it so the result is iterable, meaning that if you try and loop through it, it will automagically call mysqli_fetch_array on that result, and return you the results.
Additionally, mysql_fetch_array will return one row from the database, and is not able to be looped through via foreach. Perhaps you were thinking of mysqli_fetch_all? This returns all rows and can be looped through (Although is a bit less performant than using a while loop with mysqli_fetch_array)
$ress = mysqli_query($connect, $query);
This line returns a result set which is Traversable. So your second foreach works fine.
whereas the following line (mysqli_fetch_array) gets one row at a time and makes it an array.
$result = mysqli_fetch_array($ress); // Suppose you have 3 rows, Now cursor is at row 1
echo $result["ID"]; // this will print FIRST row's ID
$result = mysqli_fetch_array($ress); // Now cursor is at row 2
echo $result["ID"]; // this will print SECOND row's ID.
$result = mysqli_fetch_array($ress); // Now cursor is at row 3
echo $result["ID"]; // this will print THIRD row's ID.
To echo all IDs
while($result = mysqli_fetch_array($ress)) {
echo $result["ID"];
}
*MySQL will be upgraded later.
Preface: Authors can register in two languages and, for various additional reasons, that meant 2 databases. We realize that the setup appears odd in the use of multiple databases but it is more this abbreviated explanation that makes it seem so. So please ignore that oddity.
Situation:
My first query produces a recordset of authors who have cancelled their subscription. It finds them in the first database.
require_once('ConnString/FirstAuth.php');
mysql_select_db($xxxxx, $xxxxxx);
$query_Recordset1 = "SELECT auth_email FROM Authors WHERE Cancel = 'Cancel'";
$Recordset1 = mysql_query($query_Recordset1, $xxxxxx) or die(mysql_error());
$row_Recordset1 = mysql_fetch_assoc($Recordset1);
In the second db where they are also listed, (table and column names are identical) I want to update them because they cancelled. To select their records for updating, I want to take the first recordset, put it into an array, swap out the connStrings, then search using that array.
These also work.
$results = array();
do {
results[] = $row_Recordset1;
} while ($row_Recordset1 = mysql_fetch_assoc($Recordset1));
print_r($results);
gives me an array. Array ( [0] => Array ( [auth_email] => renault#autxxx.com ) [1] => Array ( [auth_email] => rinaldi#autxxx.com ) [2] => Array ( [auth_email] => hemingway#autxxx.com )) ...so I know it is finding the first set of data.
Here's the problem: The query of the second database looks for the author by auth_email if it is 'IN' the $results array, but it is not finding the authors in the 2nd database as I expected. Please note the different connString
require_once('ConnString/SecondAuth.php');
mysql_select_db($xxxxx, $xxxxxx);
$query_Recordset2 = "SELECT auth_email FROM Authors WHERE auth_email IN('$results')";
$Recordset2 = mysql_query($query_Recordset2, $xxxxxx) or die(mysql_error());
$row_Recordset2 = mysql_fetch_assoc($Recordset2);
The var_dump is 0 but I know that there are two records in there that should be found.
I've tried various combinations of IN like {$results}, but when I got to "'$results'", it was time to ask for help. I've checked all the available posts and none resolve my problem though I am now more familiar with the wild goose population.
I thought that since I swapped out the connection string, maybe $result was made null so I re-set it to the original connString and it still didn't find auth_email in $results in the same database where it certainly should have done.
Further, I've swapped out connStrings before with positive results, so... hmmm...
My goal, when working, is to echo the Recordset2 into a form with a do/while loop that will permit me to update their record in the 2nd db. Since the var_dump is 0, obviously this below isn't giving me a list of authors in the second table whose email addresses appear in the $results array, but I include it as example of what I want use to start the form in the page.
do {
$row_Recordset2['auth_email_addr '];
} while($row_Recordset2 = mysql_fetch_assoc($Recordset2));
As always, any pointer you can give are appreciated and correct answers are Accepted.
If you have a db user that has access to both databases and tables, just use a cross database query to do the update
UPDATE
mydb.Authors,
mydb2.Authors
SET
mydb.Authors.somefield = 'somevalue'
WHERE
mydb.Authors.auth_email = mydb2.Authors.auth_email AND
mydb2.Authors.Cancel= 'Cancel'
The IN clause excepts variables formated like this IN(var1,var2,var3)
You should use function to create a string, containing variables from this array.
//the simplest way to go
$string = '';
foreach($results as $r){
foreach($r as $r){
$string .= $r.",";
}
}
$string = substr($string,0,-1); //remove the ',' from the end of string
Its not tested, and obviously not the best way to go, but to show you the idea of your problem and how to handle it is this code quite relevant.
Now use $string instead of $results in query
Hello stackoverflow, long time lurker first time asker. Anyways I am creating a project for my school and it is almost completely finished but I think I need help with the while loop. I am trying to sum the variables that are stored in the array and then output that into a useable variable that I can sum with another variable. The problem is the loop only does 1 iteration every time I refresh to page. So it will eventually get the full array but only one item at a time. Please let me know what I am going wrong, I'm sure its something dumb!
$bill= mysql_query("SELECT Transaction.date, Transaction.Price, Transaction.customer_customer_id, Service.cost, Service.user_id, Service.uname
FROM *.Transaction,*.Service
WHERE Transaction.customer_customer_id = Service.user_id AND Service.uname = '$uuname'");
$query_row=mysql_fetch_array($bill);
$userservice = ($query_row[cost]);
$userprice = ($query_row[Price]);
$row2=array();
while($row = mysql_fetch_array($bill))
{
$row2[] += $row['cost'];
}
$totalservice = array_sum($row2);
Thanks for any help you guys may have. This one is frying my brain.
Both your SQL and your PHP make no sense.
FROM *.Transaction,*.Service
...will throw an error in MySQL, but your code doesn't check for errors. I suspect it should be:
FROM Transaction, Service
While the PHP will parse and run.....
while($row = mysql_fetch_array($bill)) {
$row2[] += $row['cost'];
}
$totalservice = array_sum($row2);
Is a very strange way to populate an array. Why not just....
while($row = mysql_fetch_array($bill)) {
$totalservice+=$row['cost'];
}
Indeed, if you are just throwing away the rest of the data, then why are you fetching it from the database?
SELECT SUM(Service.cost)
FROM Transaction,Service
WHERE Transaction.customer_customer_id = Service.user_id
AND Service.uname = '$uuname'
In which case the join is also redundant:
SELECT SUM(Service.cost)
FROM Service
WHERE Service.uname = '$uuname'
Rewrite query as
SELECT Service.user_id, Service.uname, SUM(Service.cost) as cost
FROM djqrico_hotel.Transaction LEFT JOIN djqrico_hotel.Service ON Transaction.customer_customer_id = Service.user_id
WHERE Service.uname = '$uuname' GROUP BY Service.user_id
if you want to get sum of all user's transactions.
The problem is the loop only does 1 iteration every time I refresh to page.
Have you ran the query against the database and checked if it's returning more than one row?
Also, if all you want to do is sum the cost column you could do that in sql:
SELECT SUM(cost)[....]
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Is it possible to query a tree structure table in MySQL in a single query, to any depth?
I have an admin area I created that pulls data from the mysql database using php and display the results in a table. Basically it shows a parent category, then the first sub category below it, then the third level sub category/subject.
It works perfectly but as I am new to mysql and php I am sure that it the code needs to be improved in order to save db resources as while building the table I use 3 while loops and in each loop make a mysql query which I am sure is the wrong way to do it.
Can somebody offer me some assistance for the best way of doing this?
Here is the code:
$query = mysql_query("SELECT * FROM categories WHERE
parent_id is null
order by cat_id asc;", $hd)
or die ("Unable to run query");
while ($row = mysql_fetch_assoc($query)) {
echo '<tr style="font-weight:bold;color:green;"><td>'. $row ['cat_id'].'</td><td>'.$row['cat_name'].'</td><td>'.$row ['parent_id'].'</td><td>'.$row['active'].'</td><td>'.$row ['url'].'</td><td>'.$row['date_updated'].'</td></tr>' ;
$query2 = mysql_query("SELECT * FROM categories WHERE
(active = 'true' AND parent_id = ".$row ['cat_id'].")
order by cat_id asc;", $hd)
or die ("Unable to run query");
while ($row2 = mysql_fetch_assoc($query2)) {
echo '<tr style="font-weight:bold;"><td>'. $row2['cat_id'].'</td><td>'.$row2 ['cat_name'].'</td><td>'.$row2['parent_id'].'</td><td>'.$row2 ['active'].'</td><td>'.$row2['url'].'</td><td>'.$row2 ['date_updated'].'</td></tr>' ;
$query3 = mysql_query("SELECT * FROM categories WHERE
(active = 'true' AND parent_id = ".$row2 ['cat_id'].")
order by cat_id asc;", $hd)
or die ("Unable to run query");
while ($row3 = mysql_fetch_assoc($query3)) {
echo '<tr><td>'. $row3['cat_id'].'</td><td>'.$row3['cat_name'].'</td><td>'.$row3 ['parent_id'].'</td><td>'.$row3['active'].'</td><td>'.$row3 ['url'].'</td><td>'.$row3['date_updated'].'</td></tr>' ;
}
}
}
EDIT
Ok so I did a bit of research and this is where I am:
Probably for a small database my approach is fine.
For a bigger database using an array to store the data would probably mean I need to use a recursive approach which might use up too much memory. Would love to hear what people think, would it still be better than looping db queries in the nested while loops?
I found the following thread where there is an answer to do this without reccursion and with only one query. Not sure if I need to add a position column to my current design:
How to build unlimited level of menu through PHP and mysql
If I rebuild the design using the nested sets model instead of adjacency model then the mysql query would return the results in the required order however maintaining the nested sets design is above my head and I think would be overkill.
That's it. If anyone has any input on top of that please add to the conversation. There must be a winning approach as this kind of requirement must be needed for loads of web applications.
I would think you could do something like this:
SELECT * FROM categories
WHERE active = 'true'
ORDER BY parent_id, cat_id
This would give you all your categories ordered by parent_id, then by cat_id. You would then take the result set and build a multi-dimensional array from it. You could then loop through this array much as you currently do in order to output the categories.
While this is better from a DB access standpoint, it would also consume more memory as you need to keep this larger array in memory. So it really is a trade-off that you need to consider.
There is a lot to fix there, but I'll just address your question about reducing queries. I suggest getting rid of the WHERE clauses all together and use if statements within the while loop. Use external variables to hold all the results that match a particular condition, then echo them all at once after the loop. Something like this (I put a bunch of your stuff in variables for brevity)
//before loop
$firstInfoSet = '';
$secondInfoSet = '';
$thirdInfoSet = '';
//in while loop
if($parentID == NULL)
{
$firstInfoSet.= $yourFirstLineOfHtml;
}
if($active && $parentID == $catID) // good for query 2 and 3 as they are identical
{
$secondInfoSet.= $yourSecondLineOfHtml;
$thirdInfoSet.= $yourThirdLineOfHtml;
}
//after loop
echo $firstInfoSet . $secondInfoSet . $thirdInfoSet;
You can now make whatever kinds of groupings you want, easily modify them if need be, and put the results wherever you want.
--EDIT--
After better understanding the question...
$query = mysql_query("SELECT * FROM categories order by cat_id asc;", $hd);
$while ($row = mysql_fetch_assoc($query)){
if($row['parent_id'] == NULL){
//echo out your desired html from your first query
}
if($row['active'] && $row['parent_id']== $row['cat_id']){
//echo out your desired html from your 2nd and 3rd queries
}
}
This is the query I have:
$sqlw = "SELECT * FROM coverages where user_id='3828' ORDER BY sp_id ASC";
$resultw = mysql_query($sqlw);
$roww = mysql_fetch_array($resultw);
while ($roww = mysql_fetch_array($resultw)) {
echo $roww['sp_id']."<br>";
}
echo "TOTAL:".mysql_num_rows($resultw)."<br>";
As you can see its very basic
the results show : TOTAL:29
But when I count the list of the items returned back its only 28.
I ran the query on phpmyadmin it shows a total of 29 rows, I did count them and they are 29.
I ran different other simple queries and it always does the same thing: one row is missing. This could be trivial maybe I am missing something or maybe its server related? any help/ideas would be greatly appreciated. Thank you
Your call to mysql_fetch_array() before the loop disposes of a row.
You have a classic off-by-one error.
There is an extra $roww = mysql_fetch_array($resultw); before your loop starts. This means you're throwing away the first row.