I need connect in two tables... Help me please!
<?php
$tabela = mysql_query("SELECT * FROM rankpvp ORDER BY ratio DESC LIMIT 1");
while($pvp = mysql_fetch_assoc($tabela)){
$classe = mysql_query("SELECT * FROM char WHERE char_id = '".$pvp['char_id']."'");
echo ' classe: '.$classe['class'].'<br> Nome: '.$pvp['name'].'<br> Pontos: '.$pvp['ratio'].'<br> Kills: '.$pvp['kills'].'<br> '; } ?>
This can be done with one query
SELECT * FROM `char` WHERE char_id = (SELECT char_id FROM rankpvp ORDER BY ratio DESC LIMIT 1)
Note that char is a reserved word so it will have to be wrapped in back ticks. Maybe this is the actual problem you ran into (syntax error) rather than a problem with your while loop. Nevertheless, one query is the right way
Related
I need connect in two tables... Help me please!
<?php
$tabela = mysql_query("SELECT * FROM rankpvp ORDER BY ratio DESC LIMIT 1");
while($pvp = mysql_fetch_assoc($tabela)){
$classe = mysql_query("SELECT * FROM char WHERE char_id = '".$pvp['char_id']."'");
echo ' classe: '.$classe['class'].'<br> Nome: '.$pvp['name'].'<br> Pontos: '.$pvp['ratio'].'<br> Kills: '.$pvp['kills'].'<br> '; } ?>
This can be done with one query
SELECT * FROM `char` WHERE char_id = (SELECT char_id FROM rankpvp ORDER BY ratio DESC LIMIT 1)
Note that char is a reserved word so it will have to be wrapped in back ticks. Maybe this is the actual problem you ran into (syntax error) rather than a problem with your while loop. Nevertheless, one query is the right way
I'm having a little trouble with my rand() function. I have the following query:
$listTrainers = mysqli_query($conn, "SELECT emp_id FROM employees;");
while($fetchTrainers = mysqli_fetch_row($listTrainers))
{
echo 'ID: ' . $fetchTrainers['0']. '<br>';
}
This query returns me the id of all employees in the database, is there a way I can randomly select one of these id's and store it in a variable?
I am trying to use the following function:
echo(rand(begin, end));
where begin is the first element from the query and end is the last element
add this to your query:
ORDER BY RAND() LIMIT 1
You can do so within your query easily
SELECT emp_id FROM employees ORDER BY RAND() LIMIT 1
The easiest way is to do this directly in the database, to avoid getting all IDs if you only need one:
SELECT
emp_id
FROM
employees
ORDER BY
RAND()
LIMIT
1
If you do need all IDs, but additionally want to pick a random one, use this to avoid querying the database twice:
$listTrainers = mysqli_query($conn, "SELECT emp_id FROM employees;");
while($fetchTrainers = mysqli_fetch_row($listTrainers))
{
$id = $fetchTrainers[0];
echo 'ID: ' . $id . '<br>';
$ids[] = $id;
}
$randomId = $ids[array_rand($ids)];
for($nr = 0; $nr < 2; $nr++){
print $nr; print(gettype($nr)); // prints 0integer
$result = mysqli_query($con,"SELECT * FROM phcdl_files
ORDER BY file_id DESC LIMIT '$nr',1")
or die(mysqli_error($con));
}
Trying to run the query above but I'm having troubles because of syntax.
Running it on PhpMyAdmin with Limit 0,1 works good however
Any idea what's the problem?
Try with -
"SELECT * FROM phcdl_files ORDER BY file_id DESC LIMIT $nr,1"
I think the issue is that you're adding quote around the 0.
Your SQL query should look like:
"SELECT * FROM phcdl_files ORDER BY file_id DESC LIMIT $nr, 1"
remove single quotation of $nr veriable from query
QUERY = "select * from tb_name order by id desc limit $nr , 1"
I have two tables in one database. I am querying the first table limit by 10 then loop the results. And inside the while loop, I am doing again another query using a data from the first query as a parameter. Here is an example of the script:
<?php
$con = mysql_connect(host,username,password);
mysql_select_db(game_server);
//My first query
$q1 = mysql_query('SELECT * FROM game_characters ORDER BY score DESC LIMIT 10');
while($character = mysql_fetch_object($q1)){
//My second query
$q2 = mysql_query('SELECT * FROM game_board WHERE id="'.$character->id.'"');
$player = mysql_fetch_object($q2);
}
?>
So if I have a result of 100 rows, then the second query will execute 100 times. And I know it is not good. How can I make it better. Is there a way to do everything in one query? What if there is another query inside the while loop where a data from the second query as a parameter is used?
P.S.: I am doing a rankings system for an online game.
You can do it in one query if you use JOINs.
SELECT * FROM game_board AS b
LEFT JOIN game_characters AS c ON b.id = c.id
ORDER BY c.score DESC
LIMIT 10
You can also use nested query
SELECT * FROM game_board AS b WHERE
id IN (SELECT id FROM game_characters AS c ORDER BY score DESC LIMIT 10)
You can also put all game_character.id into an array, and use
$sql = "SELECT * FROM game_board AS b WHERE b.id IN (" . implode(', ', $game_character_ids) . ")";
Why not using JOIN?
This way there will be no queries within the while loop:
$con = mysql_connect(host,username,password);
mysql_select_db(game_server);
//My first query
$q1 = mysql_query('
SELECT *
FROM game_characters gc
LEFT JOIN game_board gb ON gc.id = gb.id
ORDER BY score DESC
LIMIT 10
');
while($character = mysql_fetch_object($q1)){
// do Your stuff here, no other query...
}
A better approach here would be to collect all the IDs in a concatenated string str in form 'id1', 'id2', 'id3', ... and use:
select * from game_board where id in (str)
What about if you do something like the following:
<?php
$con = mysql_connect(host,username,password);
mysql_select_db(game_server);
//My first query
$q1 = mysql_query('SELECT * FROM game_characters ORDER BY score DESC LIMIT 10');
while($character = mysql_fetch_object($q1)){
//My second query
$characters .= " ' $character->id ' ,"
}
$q2 = mysql_query("SELECT * FROM game_board WHERE id in (substr($characters,0,strlen($characters - 2))");
$player = mysql_fetch_object($q2);
?>
I've been looking for this for a while but with no success.
I am trying to implement a recomendation bar, for example like in youtube, when you are seeing a video it shows the list or recommended videos on the right.
At this moment I am using this method:
$offset_result = mysql_query( " SELECT FLOOR(RAND() * COUNT(*)) AS `offset` FROM `$tablename` ");
$offset_row = mysql_fetch_object($offset_result );
$offset = $offset_row->offset;
$result_rand = mysql_query( " SELECT * FROM `$tablename` LIMIT $offset, 9 " );
This works fine, but sometimes doesn't show any result, and the problem is also that its not completely random, because it shows for example the first ID as 200, so the next result will be id 201 and then 202 and so.
I would like to know if there is a way to show this 9 randon results, for example 1º result id 500, 2º result id 10, 3º result id 788, etc etc?
Thank you
Not entirely sure this answers what you are looking for, but try:
$result_rand = mysql_query("SELECT * FROM " . $tablename . " ORDER BY RAND() LIMIT 9");
You can use php rand() function to create 5 numbers and save them in an array:
http://php.net/manual/en/function.rand.php
<?php
$rand_array = array();
for($i=1;$i<5;$i++) {
$rand_array[$i] = rand(0,500);
}
?>
and after that create a query with every int with a foreach loop and work with your data.
<?php
foreach ($rand_array as $integer) {
$q = "SELECT * from $tablename WHERE id='$integer';";
}
?>
Does this helps?
First you should use mysqli_ functions instead of mysql_ because the latter is deprecated. Second use order by rand() to get random rows:
$rand_result = mysqli_query( "SELECT * FROM $tablename ORDER BY RAND() LIMIT 9;" );
UNTESTED:
SELECT id, #rownum:=#rownum+1 AS rownum, name
FROM users u,
(SELECT #rownum:=0) r
THis will give a unique number to each row in sequence. Now if you create a temp table with 9 random numbers between 1 and count(*) of your table and JOIN those two together...
Not sure about performance but seems like it might be faster than Rand and order by since I only need 9 random numbers