I'm trying to show images with a specific subject on the screen. I have 5 images with the same subject and it only shows one image. If I change the subject of the image in the database, the next image with the subject I try to call appears.
function selectSubject($subject){
$showSubject = mysql_query("SELECT name FROM images WHERE subject = '$subject'");
while($showSubject = mysql_fetch_array($showSubject)){
$source_subject_trees = $showSubject['name'];
echo "<img class=\"subject_images\" src='img/$source_subject_bomen'></>";
}
};
mysql_query() returns a result handle. You then stomp all over that handle by re-assigning to it within your while() loop:
$showSubject = mysql_query(...);
while($showSubject = msyql_fetch_array($showSubject)) {
^^^^^^^^^^^^---here
mysql_fetch_array() returns an array of one row's data. Since you're assigning to the SAME variable as you stored the actual query result handle, you destroy the result handle... and end up being unable to fetch any more data, because the handle's gone.
In mysql_query you can use GROUP BY subject to get only distinct result
In mysql_query you can use DISTINCT(name) to get distinct result on selection time
Any of aboue mention option to get as per your valid result.
Related
I'm a beginner who has problems with PHP :(
I have a PHP function which shows all the rows from the database table. Now I have to create paging to show only limited number of rows per one page.
I have a problem with retrieving a COUNT result from query. I want to create a condition where PHP & MySQL use LIMIT if number of rows is bigger than needed on one page. The following code:
$count = "SELECT COUNT(*) FROM articles";
$countq = $db->query($count);
$countrs = mysql_fetch_array($countq);
echo $countrs;
should display a number of rows. However, it does not. What am I doing wrong? I want to see a result to make sure that everything else will work fine. But I can't get it working.
Error: mysql_fetch_array() expects parameter 1 to be resource, object given
$db contains database connection information (server, user...) and is working
Use PDO for MySQL query.
$db = new PDO('mysql:host=#YOUR HOST#;dbname=#YOUR DB#;charset=utf8', '#YOUR LOGIN#', '#YOUR PASSWORD#');
$query = $db->query('SELECT COUNT(*) AS count FROM articles');
$countq = $query->fetch();
$query->closeCursor();
echo $countq['count'];
I hope this will help you
You will have to set the limit in the query like
$count = "SELECT COUNT(*) FROM articles LIMIT 5,10";
where 5 is the starting point and 10 is the total number of results you want.
You mention: $db but not what $db is? i mean is it a database object class? this will work directly if you are using the a database class, and if that's the case the class will also have functions which will allow you to query data without using mysql_fetch_array (actually mysqli_fetch_array).
Is there any way to print the resource_id without mysql_fetch_array.I dont want to loop through result.I want print only the first row at top.I know mysql has been depreciated.This is for old project.
You can make use of arrays in your case
$all_rows = array();
.
. // your query
.
while($dbrow = mysql_fetch_array($query))
{
$all_rows[] = $dbrow;
}
$first_row_array = $all_rows[0]; // first row will be stored here
/*
uncomment the below line if you do not want to use the
first row again while looping through the remaining
rows
*/
/* unset($all_rows[0]); */
foreach($first_row_array as $first_row)
{
// do something with first row data
}
foreach($all_rows as $dbrow)
{
// loop through all the rows returned including the first row
}
A resource in itself is a pretty meaningless type. It only means something to specific functions, like mysql_*. When querying the database, there are certain resources allocated on the MySQL server which hold your requested result; PHP doesn't really have access to those results yet. To give you a handle on those resources on the MySQL server, you get a resource type variable. It's basically just your ticket, saying "if you ever want to access that data waiting for you on the MySQL server, use this number."
So, if you want to output the data from the MySQL server, you will have to fetch it from there, e.g. with mysql_fetch_assoc. That then returns the data to you which you can print.
If you just want the first result, just call that function once.
I have this function in a linked file:
function getNumberOfHerps() {
$sql = "SELECT COUNT(ID)
FROM HERPES;";
return DBIface::connect()->query($sql);
}
I can call on this function from any other page in the website. What I want to do is to be able to use the result of the COUNT function in my php code on various pages, because I need to know how many herps there are in the database on several occasions in the code.
I tried this:
$result = getNumberOfHerps();
$numberOfHerps = $result['COUNT'];
But it caused a parse error on the second line, saying this:
Cannot use object of type PDOStatement as array.
Please tell me how I can use the result of a Count function in php code. Thanks :D
You are actually facing 2 separate items here that need your attention:
You can't access the COUNT(ID) returned from your query and
You are attempting to access data of a PDOStatement object as an array
So:
You can create an ALIAS for the value returned from the COUNT() function:
$sql = "SELECT COUNT(ID) as COUNT...";
This will provide to your result set a new column named COUNT that you can access your row count from.
Secondly, you need to perform a fetch operation on the PDOStatement in order to access it's data (this is what is causing your parse error). You have several options for accessing the result set in a PDOStatement:
list ($idCount) = $result->fetch();
// $idCount will now have the value of your COUNT column
or
$results = $result->fetch(PDO::FETCH_ASSOC);
// you can then access your COUNT as $results['COUNT'];
or even
$results = $result->fetch(PDO::FETCH_OBJ);
// you can then access your count as $results->COUNT
There are actually several additional FETCH_* styles available to use. The ones I've described though would likely be the most common. You can find more information about fetching PDO result sets at
http://us1.php.net/manual/en/pdostatement.fetch.php
I worked it out for myself, so I'll put my answer up for anyone else who finds this question:
I changed the function to this:
function getNumberOfHerps() {
$sql = "SELECT COUNT(1)
FROM HERPES";
return DBIface::connect()->query($sql)->fetchColumn(0);
}
So what the function now returns is the actual count value (the first column of the query). That means that in the webpage php file, you can access it in this way:
$numberOfHerps = getNumberOfHerps();
Much more simple.
I am trying to figure out the proper way to get file location data (for display/editing) from MySQL with PHP. So far I've got these three parts. $resfile is a resource getting the actual array. Would I then test with an if statement, or would I have to use a while loop to iterate over the array (which, as far as I know, should only have ONE value)
First part:
$resfile = mysql_query('SELECT file_loc WHERE org_id = '.$org);
Do I use this?
if (!$resfile) {
}
Or this?
while ($filerow = mysql_fetch_array($resfile)) {
}
Or both?
The mySQL library has a function for counting the rows of a result set:
if (mysql_num_rows($resfile) > 0) .......
You need to use both. If the query returns false, then there was an error executing your query. If there is no data returned in the query, (it will still return true) then you need to use fetch_array to get the data.
I'd like to do different operations on the data returned from a single sql query, something like this:
$sql = "SELECT * FROM mandant";
$res = pg_query($_db,$sql);
while ($mandant_list = pg_fetch_object($res))
{
# do stuff
}
while ($mandant = pg_fetch_object($res))
{
# do other stuff
}
But this doesn't work. The first loop gets the data, the second one not.
Is it possible to reuse the result returned from the query without running it again?
If not, why? What happens to the $res variable?
Yes, you can "rewind" the result resource by using pg_result_seek().
It is possible.
The reason the second loop breaks is because every time you are fetching a row from the data set it is being decremented until there are no rows left in the object.
You'll need to make 2 copies of $res and then run the second while() on the second $res.