I have a DB table with 100-200k records and I need to optimize it. For example, if a user want to search the term car, he will get around 25k results.
I would like to offer him just let's say 500 newest results, but how to do that? I know I have to use LIMIT, but I am not sure, how to "group" just the newest 500 rows.
For making a better picture how I am fetching data from database now, here's a little snippet:
$search = mysql_real_escape_string(searched_query($_GET['skill']));
$q = "...long sql query...";
echo $q;
$result = mysql_query($q);
$items = 30; // number of items per page.
$all = $_GET['a'];
$num_rows = mysql_num_rows($result);
if($all == "all"){
$items = $num_rows;
}
$nrpage_amount = $num_rows/$items;
$page_amount = ceil($num_rows/$items);
$page_amount = $page_amount-1;
$page = mysql_real_escape_string($_GET['p']);
if($page < "1"){
$page = "0";
}
$p_num = $items*$page;
// Query that you would like to SHOW
$result = mysql_query($q." ORDER BY published DESC LIMIT $p_num , $items");
Thank you in advance!
By ordering by published DESC you have already ordered the list from newest to oldest. So if you apply the limit of 500, it will automatically only fetch the newest 500 rows...
So Mysql will order first, and then apply the limit.
Use ORDER BY in the query. Have a look here for more details
Related
I have a query that requests an ID (the PK) and an order number and throws them into an array. I then loop through the returned data in the array and run two more queries to find the number of times the order number shows up in the database and to get the invoice numbers that belong to that order number. The problem I'm seeing with this setup is that it is taking a while (around 9 seconds) to return the compiled data array. Is there a faster way to get the returned results I'm looking for?
I've tried to find some articles online and came across mysqli_multi_query. Is this the better route to make multiple queries to gather the type of data I am trying to get?
<?php
require 'config.php';
$sql = "SELECT id,internal_order_number FROM orders GROUP BY internal_order_number ORDER BY created_date desc LIMIT 0 ,50";
$query=mysqli_query($mysqli, $sql);
if (!$query) {
throw new Exception(mysqli_error($mysqli)."[ $sql]");
}
$data = array();
while( $row=mysqli_fetch_array($query) ) { // preparing an array
$nestedData=array();
$nestedData['line_id'] = $row["id"];
$nestedData['internal_order_number'] = $row["internal_order_number"];
$data[] = $nestedData;
}
$compiled_data = array();
// Loop through data array with additional queries
foreach($data as $line){
$new_data = array();
// Get item counts
$item_counts = array();
$get_count = " SELECT internal_order_number FROM orders WHERE internal_order_number = '".$line['internal_order_number']."' ";
$count_query=mysqli_query($mysqli, $get_count);
while ($counts=mysqli_fetch_array($count_query)){
if (isset($item_counts[$counts['internal_order_number']])) {
$item_counts[$counts['internal_order_number']]++;
} else {
$item_counts[$counts['internal_order_number']] = 1;
}
}
$product_count = $item_counts[$line['internal_order_number']];
// Get invoice numbers
$invoice_array = array();
$get_invoices = " SELECT invoice_number FROM orders WHERE internal_order_number = '".$line['internal_order_number']."'";
$invoice_query=mysqli_query($mysqli, $get_invoices);
while ($invoice=mysqli_fetch_array($invoice_query)){
if(!in_array($invoice['invoice_number'], $invoice_array)){
$invoice_array[] = $invoice['invoice_number'];
}
}
$invoices = implode(", ",$invoice_array);
$new_data['order_number'] = $line['internal_order_number'];
$new_data['count'] = $product_count;
$new_data['invoices'] = $invoices;
$compiled_data[] = $new_data;
}
mysqli_close($mysqli);
print_r($compiled_data);
?>
What, why are you doing basically the same query 3 times. You first one selects them all, you second query requires the same table making sure the first tables order number == the tables order number and the last just grabs the invoice number...?
Just do one query:
SELECT internal_order_number, invoice_number FROM table WHERE ...
Then loop through it and do what you need. You don't need 3 queries...
I'm trying to create a pagination for my PDO query. I cant figure it out. I've tried numerous google searches, but nothing that will work for me. [I probably didn't search hard enough. I'm not sure]
This is my code:
$sql2 = "SELECT * FROM comments WHERE shown = '1'ORDER BY ID DESC";
$stm2 = $dbh->prepare($sql2);
$stm2->execute();
$nodes2= $stm2->fetchAll();
foreach ($nodes2 as $n1) {
echo "text";
}
I want to be able to limit 10 comments per page, and use $_GET['PAGE'] for the page.
Something that I tried
$sql2 = "SELECT * FROM comments WHERE shown = '1'ORDER BY ID DESC";
$stm2 = $dbh->prepare($sql2);
$stm2->execute();
$nodes2= $stm2->fetchAll();
$page_of_pagination = 1;
$chunked = array_chunk($nodes2->get_items(), 10);
foreach ($chunked[$page_of_pagination] as $n1) {
echo "text";
}
If someone could help out, I appreciate it.
You need to limit the query that you are performing, getting all values from the database and then limiting the result to what you want is a bad design choice because it's highly inefficient.
You need to do this:
$page = (int)$_GET['PAGE']; // to prevent injection attacks or other issues
$rowsPerPage = 10;
$startLimit = ($page - 1) * $rowsPerPage; // -1 because you need to start from 0
$sql2 = "SELECT * FROM comments WHERE shown = '1' ORDER BY ID DESC LIMIT {$startLimit}, {$rowsPerPage}";
What LIMIT does:
The LIMIT clause can be used to constrain the number of rows returned by the SELECT statement. LIMIT takes one or two numeric arguments, which must both be nonnegative integer constants
More information here: http://dev.mysql.com/doc/refman/5.7/en/select.html
Then you can proceed getting the result and showing it.
Edit after comment:
To get all the pages for display you need to know how many pages are there so you need to do a count on that SELECT statement using the same filters, meaning:
SELECT COUNT(*) as count FROM comments WHERE shown = '1'
Store this count in a variable. To get the number of pages you divide the count by the number of rows per page you want to display and round up:
$totalNumberOfPages = ceil($count / $rowsPerPage);
and to display them:
foreach(range(1, $totalNumberOfPages) as $pageNumber) {
echo '' . $pageNumber . '';
}
How to get total number of rows for particular query and also limiting the query results to 10 rows. For example. I've a table called sample. It has 400 rows. On running a query like where name = "%Sam%" it returns me 213 rows. Now I'l be taking only first 10 rows and displaying the result to user but I need the total rows returned. How should I need to do it in code igniter?
SELECT
SQL_CALC_FOUND_ROWS *
FROM
sample
WHERE
name like "%sam%"
like this?
How to retrieve total number counts?
You need to run a second query to get the results of SQL_CALC_FOUND_ROWS:
SELECT FOUND_ROWS()
That will return the value found using SQL_CALC_FOUND_ROWS. You may find using an alias easier for getting the result, though:
SELECT FOUND_ROWS() AS num_results
You can use two query one to get the count and the other return the limited result.
Like in your model create a function that only returns the count variable
and create a second function that generates the paginated results.
eg..
public function count($where){
$query = $this->db->query("select count(id) as count from clients $where");
return $query->row('count');
}
}
public function limit($sidx,$sord,$start,$limit,$where){
$query = $this->db->query("select * from clients $where ORDER BY $sidx $sord LIMIT $start , $limit");
if ($query->num_rows() > 0){
return $query->result_array();
}
}
And here goes the controller code
$where = // calculated
$count = count($this->model->count($where));
if( $count > 0 ) { $total_pages = ceil($count/$limit); } else { $total_pages = 0; }
if ($page > $total_pages) $page = $total_pages;
$start = $limit * $page - $limit;
$users = $this->model->limit($sidx,$sord,$start,$limit,$where);
.................
Hi I am trying to display my users data over pages
Here is my code:
//Run a query to select all the data from the users table
$perpage = 2;
$result = mysql_query("SELECT * FROM users LIMIT $perpage");
It does display this the only two per page but I was wondering how you get page numbers at the bottom that link to your data
here is my updated code
$result = mysql_query("SELECT * FROM users"); // Let's get the query
$nrResults=mysql_num_rows($result); // Count the results
if (($nrResults%$limit)<>0) {
$pmax=floor($nrResults/$limit)+1; // Divide to total result by the number of query
// to display per page($limit) and create a Max page
} else {
$pmax=floor($nrResults/$limit);
}
$result = mysql_query("SELECT * FROM users LIMIT 2 ".(($_GET["page"]-1)*$limit).", $limit");
// generate query considering limit
while($line = mysql_fetch_array( $result ))
{
?>
error
Parse error: syntax error, unexpected $end in E:\xampp\htdocs\Admin.php on line 98
In order to do this you also need to use the offset value in your SQL Statement, so it would be
SELECT * FROM users LIMIT $offset, $perpage
Example:
SELECT * FROM tbl LIMIT 5,10; # Retrieve rows 6-15
Then to get the links to put on the bottom of your page you would want to get a count of the total data, divide the total by the per page value to figure out how many pages you are going to have.
Then set your offset value based on what page the user clicked.
Hope that helps!
Update:
The unexpected end most likely means that you have an extra closing bracket } in your code which is causing the page to end and still has more code after it. Look through your code and match up the brackets to fix that. There are a few other issues in the code sample you pasted.
$result = mysql_query("SELECT * FROM users" ); //Note if you have a very large table you probably want to get the count instead of selecting all of the data...
$nrResults = mysql_num_rows( $result );
if( $_GET['page'] ) {
$page = $_GET['page']
} else {
$page = 1;
}
$per_page = 2;
$offset = ($page - 1) * $per_page; //So that page 1 starts at 0, page 2 starts at 2 etc.
$result = mysql_query("SELECT * FROM users LIMIT $offset,$per_page");
while( $line = mysql_fetch_array( $result ) )
{
//Do whatever you want with each row in here
}
Hope that helps
You can then use the nrResults number to figure out how many pages you are going to have... if you have 10 records and you are displaying 2 per page you would then have 5 pages, so you could print 5 links on the page each with the correct page # in the URL...
Use requests ! http://php.net/manual/en/reserved.variables.request.php
if (((isset($_GET['page'])) AND (is_int($_GET['page']))) {
$perpage = $_GET['page'];
}
$result = mysql_query("SELECT * FROM users LIMIT $perpage");
...
Link http://yourwebsite.com/userlistforexample.php?page=3
or
http://yourwebsite.com/userlistforexample.php?somethingishere=21&page=3
how can i check current number in mysql where....
my query is
$aid = 16;
$get_prev_photo = mysql_query("SELECT * FROM photos WHERE album_id='$aid' AND pic_id<'$picid' ORDER BY pic_id LIMIT 1");
$get_next_photo = mysql_query("SELECT * FROM photos WHERE album_id='$aid' AND pic_id>'$picid' ORDER BY pic_id LIMIT 1");
while i am getting current photo with following query
$photo = mysql_query("SELECT * FROM photos WHERE pic_id='$picid' LIMIT 1");
and getting total photos in album with following query
$photos = mysql_query("SELECT * FROM photos WHERE album_id='$aid'");
$total_photos = mysql_num_rows($photos);
now i want to check where i am and show it as Showing 1 of 20, showing 6 of 20 and so on...
now i want to check where i am actually...
i think you are referring to pagination, which can be achieved using LIMIT and OFFSET sql
decide the number of results you want per page, then select that many
create links like:
View the next 10
and dynamically change those every time
queries look ~like~
$offset=$_GET['view'];
SELECT * FROM table WHERE `condition`=true LIMIT 5 OFFSET $offset
this translates roughly as
select 5 from the table, starting at the 10th record
This is bad:
$photos = mysql_query("SELECT * FROM photos WHERE album_id='$aid'");
Because it grabs all the fields for the entire album of photos when all you really want is the count. Instead, get the total number of photos in the album like this:
$result = mysql_query("SELECT count(1) as total_photos FROM photos
WHERE album_id='$aid'");
if ($result === false) {
print mysql_error();
exit(1);
}
$row = mysql_fetch_object($result);
$total_photos = $row->total_photos;
mysql_free_result($result);
Now you have the count of the total number of photos in the album so that you can set up paging. Let's say as an example that the limit is set to 20 photos per page. So that means that you can list photos 1 - 20, 21 - 40, etc. Create a $page variable (from user input, default 1) that represents the page number you are on and $limit and $offset variables to plug into your query.
$limit = 20;
$page = $_POST['page'] || 1; // <-- or however you get user input
$offset = $limit * ($page - 1);
I'll leave the part where you code the list of pages up to you. Next query for the photos based on the variables you created.
$result = mysql_query("SELECT * FROM photos WHERE album_id='$aid'
ORDER BY pic_id LIMIT $limit OFFSET $offset");
if ($result === false) {
print mysql_error();
exit(1);
}
$photo_num = $offset;
while ($row = mysql_fetch_object($result)) {
$photo_num++;
$pic_id = $row->pic_id;
// get the rest of the variables and do stuff here
// like print the photo number for example
print "Showing photo $photo_num of $total_photos\n";
}
mysql_free_result($result);
I'll leave better error handing, doing something with the data, and the rest of the details up to you. But that is the basics. Also I did not check my code for errors so there might be some syntax problems above. To make a single photo per page just make $limit = 1.