I have a table photos with many photos in it and I need to select two at random:
In getnew.php
$result = mysqli_query($conn,"SELECT * FROM photos ORDER BY rand() LIMIT 1");
$result2 = mysqli_query($conn,"SELECT * FROM photos ORDER BY rand() LIMIT 1");
$row = $result->fetch_assoc();
$img1link = $row['link'];
// more stuff from $row
$row2 = $result2->fetch_assoc();
$img2link = $row2['link'];
// more stuff from $row2
However I need to prevent it from selecting the same photo twice (the selected photos must be different), i.e. $img1link should not = $img2link. I then need to retrieve the data using $.getJSON in another file, using an array at the end of getnew.php.
The array at the end of getnew.php:
echo json_encode(array('img1'=>$img1link,'img2'=>$img2link, ...(etc)... ));
How can I make sure the selected photos are different by the time the variable is stored in the array? I tried to create an if/else statement but didn't really understand what I was doing.
You can just execute once but get two instead so that you'll never pick the same row:
$result = mysqli_query($conn,"SELECT * FROM photos ORDER BY rand() LIMIT 2");
$row = $result->fetch_assoc();
$row2 = $result->fetch_assoc();
// invoke `->fetch` twice to get the first and second row
$img1link = $row['link'];
$img2link = $row2['link'];
Sidenote: Be careful of that ORDER BY rand() clause since it'll be slow on large data sets. You can use an alternative with #Bill Karwin's great answer
Run a single query -
$result1 = mysqli_query($conn,"SELECT * FROM photos ORDER BY rand() LIMIT 2");
while($row = $result->fetch_assoc()) {
$imglink[] = $row['link'];
}
You will get the links in $imglink[] array.
I have a MySQL database and I need a PHP to pull a random row. I have successfully created
$query = "SELECT * FROM $usertable
WHERE region='UK'
ORDER BY RAND() LIMIT 1";
This successfully randomly pulls a row; however, it is not limited to where region=2.
I need to be able to:
pull randomly when region=UK
pull randomly when region=UK or ##
(where ## is actually another region, for example, YK = Yorkshire)
Basically I need it to select rows randomly but ONLY when region=UK.
region is a label for one of my fields/collumns, and UK is the content of the VARCHAR in that for a number of rows.
I have the rest of the code sorted.
I have a simple database and the php as follows:
<?php
//Sample Database Connection Syntax for PHP and MySQL.
//Connect To Database
$hostname="carbonmarketing.db.9606426.hostedresource.com";
$username="MarketReadOnly";
$password="Read0nly1";
$dbname="carbonmarketing";
$usertable="ClientList";
$advertfooter = "advertfooter";
mysql_connect($hostname,$username, $password) or die ("<html>%MINIFYHTML4333ddb1f6ba50276851b9f9854a5c817%</html>");
mysql_select_db($dbname);
# Check If Record Exists
$query = "SELECT * FROM $usertable
WHERE region='UK'
ORDER BY RAND() LIMIT 1";
$result = mysql_query($query);
if($result)
{
while($row = mysql_fetch_array($result))
{
$advertfooter = $row["$advertfooter"];
echo "$advertfooter";
}
}
?>
But, it's just pulling randomly for all values of the region column
Let me know if it would help for you to see the database.
Make and array with your regions and implode them:
$region = array('UK', 'YK');
$implode = implode("', '", $region);
$query = "SELECT * FROM `".$usertable."` WHERE `region` IN ('".$implode."') ORDER BY RAND() LIMIT 1";
$query = "SELECT * FROM $usertable
WHERE region IN ('UK','YK')
ORDER BY RAND() LIMIT 1";
What would be the most efficient way to SELECT this, then DELETE it immediately.
SELECT * from `usersOnline` WHERE timestamp>NOW()-INTERVAL 5 SECOND ORDER BY rand() LIMIT 1;
How could I take this same select query, but also make it delete what it selected in the most efficient way?
$query = 'SELECT * FROM `usersOnline` WHERE timestamp>NOW()-INTERVAL 5 SECOND ORDER BY rand() LIMIT 1;';
$result = mysql_query($query);
$record = mysql_fetch_assoc($result);
$query = 'DELETE FROM `usersOnline` WHERE id = ' . $record['id'];
mysql_query($query);
with mysql, you would have to do one and then the other. you would use the key from the select result to then delete that record directly afterwards. in this example, i am assuming your primary key column is named "id". you would replace the myssql functions with whichever method you are using to access the database of course.
you can do like this nested query
DELETE
FROM SomeTable
WHERE EXISTS
(SELECT * from `usersOnline` WHERE timestamp>NOW()-INTERVAL 5 SECOND ORDER BY rand() LIMIT 1;
)
thanks
use DELETE FROM: http://dev.mysql.com/doc/refman/5.0/en/delete.html
I know this example mixed prepared statments with regular statements. But it's up to the developer how to write the code. This is just a proof of concept, kept simple for easy reading.
$mysqli = new mysqli('localhost', 'user', 'password', 'userTable');
$result = $mysqli->query("SELECT * from `usersOnline` WHERE timestamp>NOW()-INTERVAL 5 SECOND ORDER BY rand() LIMIT 1");
$stmt = $mysqli->prepare("DELETE FROM 'usersOnline WHERE id = ?");
while ($row = mysql_fetch_assoc($result)) {
$stmt->bind_param('i', $row["id"]);
$stmt->execute();
}
$stmt->close();
$mysqli->close();
I'm trying to get a pick from my DB that would last for a day (daily pick). I use the following code:
$query = 'SELECT * FROM table ORDER BY rand() LIMIT 1
But as you can see it only gives me a random pick from the table, and every time I refresh the page it gets me a new random pick. How can I make the pick to last for a whole day?
Thanks in advance <3
I'm trying this:
$query = "SELECT * FROM table ORDER BY rand(" . date("Ymd") . ") LIMIT 1";
But I get the following error: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource. This is the part that gets broken:
$results = mysql_query($query);
while($line = mysql_fetch_assoc($results))
So... it should look like this, right? (I mean, choosing the daily random pick?)
$dailyPick = 'SELECT * FROM table ORDER BY rand() LIMIT 1';
$cacheKey = 'dailyPick'. date('dmY');
if($cache->has($cacheKey)) {
$dailyPick = $cache->get($cacheKey);
} else {
// hit database
$dailyPick = $cache->save($cacheKey);
}
I'm trying this now:
$dailyPick = 'SELECT * FROM table ORDER BY rand() LIMIT 1';
$cacheKey = 'dailyPick'. date('dmY');
if($cache->has($cacheKey)) {
$dailyPick = $cache->get($cacheKey);
} else {
// hit database
$dailyPick = $cache->save($cacheKey);
}
However, it gets me a mistake that I'm using the 'has' function on a non-object.
If you set the SEED for the rand to an integer value that changes daily, that would solve your problem
$query = "SELECT * FROM table ORDER BY rand(" . date("Ymd") . ") LIMIT 1";
Would do the trick.
A sane means of doing this would be to automatically generate the pick of the day content via a cron job that was setup to run once a day.
As such, the cron job would execute the SQL you provided and store the appropriate content in a flat file/database table, etc. (or perhaps even just store the choosen id in another table for future lookup purposes).
You can try something like this:
$total = 'SELECT COUNT(*) FROM table;';
$query = 'SELECT * FROM table ORDER BY id ASC LIMIT 1 OFFSET ' . (date('Ymd') % $total) . ';';
I think you'll need to update the random picked record with "today" field = 1..
Something like this:
// ------------
// Run this 3 commands once a day
// Reset all records
mysql_query("UPDATE `table` SET `today` = 0");
// Pick one
$sql = mysql_query("SELECT `id` FROM `table` ORDER BY RAND() LIMIT 1");
$id = mysql_result($sql, 0, 'id');
// Update the record
mysql_query("UPDATE `table` SET `today` = 1 WHERE `id` = {$id}");
// ------------
// Now you can find again your "random found record":
$query = mysql_query("SELECT * FROM `table` WHERE `today` = 1");
What's the best way with PHP to read a single record from a MySQL database? E.g.:
SELECT id FROM games
I was trying to find an answer in the old questions, but had no luck.
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$id = mysql_result(mysql_query("SELECT id FROM games LIMIT 1"),0);
$link = mysql_connect('localhost','root','yourPassword')
mysql_select_db('database_name', $link);
$sql = 'SELECT id FROM games LIMIT 1';
$result = mysql_query($sql, $link) or die(mysql_error());
$row = mysql_fetch_assoc($result);
print_r($row);
There were few things missing in ChrisAD answer. After connecting to mysql it's crucial to select database and also die() statement allows you to see errors if they occur.
Be carefull it works only if you have 1 record in the database, because otherwise you need to add WHERE id=xx or something similar to get only one row and not more. Also you can access your id like $row['id']
Using PDO you could do something like this:
$db = new PDO('mysql:host=hostname;dbname=dbname', 'username', 'password');
$stmt = $db->query('select id from games where ...');
$id = $stmt->fetchColumn(0);
if ($id !== false) {
echo $id;
}
You obviously should also check whether PDO::query() executes the query OK (either by checking the result or telling PDO to throw exceptions instead)
Assuming you are using an auto-incrementing primary key, which is the normal way to do things, then you can access the key value of the last row you put into the database with:
$userID = mysqli_insert_id($link);
otherwise, you'll have to know more specifics about the row you are trying to find, such as email address. Without knowing your table structure, we can't be more specific.
Either way, to limit your SELECT query, use a WHERE statement like this:
(Generic Example)
$getID = mysqli_fetch_assoc(mysqli_query($link, "SELECT userID FROM users WHERE something = 'unique'"));
$userID = $getID['userID'];
(Specific example)
Or a more specific example:
$getID = mysqli_fetch_assoc(mysqli_query($link, "SELECT userID FROM users WHERE userID = 1"));
$userID = $getID['userID'];
Warning! Your SQL isn't a good idea, because it will select all rows (no WHERE clause assumes "WHERE 1"!) and clog your application if you have a large number of rows. (What's the point of selecting 1,000 rows when 1 will do?) So instead, when selecting only one row, make sure you specify the LIMIT clause:
$sql = "SELECT id FROM games LIMIT 1"; // Select ONLY one, instead of all
$result = $db->query($sql);
$row = $result->fetch_assoc();
echo 'Game ID: '.$row['id'];
This difference requires MySQL to select only the first matching record, so ordering the table is important or you ought to use a WHERE clause. However, it's a whole lot less memory and time to find that one record, than to get every record and output row number one.
One more answer for object oriented style. Found this solution for me:
$id = $dbh->query("SELECT id FROM mytable WHERE mycolumn = 'foo'")->fetch_object()->id;
gives back just one id. Verify that your design ensures you got the right one.
First you connect to your database. Then you build the query string. Then you launch the query and store the result, and finally you fetch what rows you want from the result by using one of the fetch methods.
$link = mysql_connect('localhost','root','yourPassword')
mysql_select_db('database',$link);
$sql = 'SELECT id FROM games'
$result = mysql_query($sql,$link);
$singleRow = mysql_fetch_array($result)
echo $singleRow;
Edit: So sorry, forgot the database connection. Added it now
'Best way' aside some usual ways of retrieving a single record from the database with PHP go like that:
with mysqli
$sql = "SELECT id, name, producer FROM games WHERE user_id = 1";
$result = $db->query($sql);
$row = $result->fetch_row();
with Zend Framework
//Inside the table class
$select = $this->select()->where('user_id = ?', 1);
$row = $this->fetchRow($select);
The easiest way is to use mysql_result.
I copied some of the code below from other answers to save time.
$link = mysql_connect('localhost','root','yourPassword')
mysql_select_db('database',$link);
$sql = 'SELECT id FROM games'
$result = mysql_query($sql,$link);
$num_rows = mysql_num_rows($result);
// i is the row number and will be 0 through $num_rows-1
for ($i = 0; $i < $num_rows; $i++) {
$value = mysql_result($result, i, 'id');
echo 'Row ', i, ': ', $value, "\n";
}
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$db = new mysqli('localhost', 'tmp', 'tmp', 'your_db');
$db->set_charset('utf8mb4');
if($row = $db->query("SELECT id FROM games LIMIT 1")->fetch_row()) { //NULL or array
$id = $row[0];
}
I agree that mysql_result is the easy way to retrieve contents of one cell from a MySQL result set. Tiny code:
$r = mysql_query('SELECT id FROM table') or die(mysql_error());
if (mysql_num_rows($r) > 0) {
echo mysql_result($r); // will output first ID
echo mysql_result($r, 1); // will ouput second ID
}
Easy way to Fetch Single Record from MySQL Database by using PHP List
The SQL Query is SELECT user_name from user_table WHERE user_id = 6
The PHP Code for the above Query is
$sql_select = "";
$sql_select .= "SELECT ";
$sql_select .= " user_name ";
$sql_select .= "FROM user_table ";
$sql_select .= "WHERE user_id = 6" ;
$rs_id = mysql_query($sql_select, $link) or die(mysql_error());
list($userName) = mysql_fetch_row($rs_id);
Note: The List Concept should be applicable for Single Row Fetching not for Multiple Rows
Better if SQL will be optimized with addion of LIMIT 1 in the end:
$query = "select id from games LIMIT 1";
SO ANSWER IS (works on php 5.6.3):
If you want to get first item of first row(even if it is not ID column):
queryExec($query) -> fetch_array()[0];
If you want to get first row(single item from DB)
queryExec($query) -> fetch_assoc();
If you want to some exact column from first row
queryExec($query) -> fetch_assoc()['columnName'];
or need to fix query and use first written way :)