i need to find the most recent element, the field "data_caricamento" save the date.
so i made a index with MognoDb shell:
db.collection.ensureIndex({"data_caricamento": -1})
and with the php code below i have what i need
$cursor=$collection->find();
$cursor->sort(array("data_caricamento"=> -1));
$cursor->limit($n);
but i think that should be a better way to do it,
for example there is a way to query the directly the index?
thx.
there is a way to query the directly the index?
Sort of. You can do a covered query here by doing:
$cursor = $collection
->find(array(), array('_id' => 0, 'data_caricamento' => 1))
->sort(array("data_caricamento" => -1))
->limit($n);
That will query only the index.
Try using the hint. And if you want to check whether the indexes got used by your query use explain().
....
$collection->find()->sort(array('data_caricamento'=>1))->hint(array('data_caricamento'=>1));
print_r($cursor->explain());
This will help you see that your queries are hitting index for faster search and sorting!
Cheers!
Related
I'm performing a simple request to my MongoDB in php. It looks like this:
$result = $this->myMongoClient->myCollection->find([
'param_1' => $param_1,
'param_2' => $param_2,
]);
This returns a MongoDB\Driver\Cursor object. I need the count of returned entrys from the database.
I've googeld a while and found this. But with this function dose not exists on the object returend by MongoDB (Call to undefined method MongoDB\Driver\Cursor::count())
$result->count()
Which is the commun way to count the number of results?
I have found a solution, but don't know if it is recommendable or not.
count($result->toArray());
I don't know if you are using the MongoDB PHP Library, but if you are you can just use the following
$result = $this->myMongoClient->myCollection->countDocuments($where);
https://docs.mongodb.com/php-library/master/reference/method/MongoDBCollection-countDocuments/index.html
Database table SITE has many columns. One of them is site_id. I need all the site_ids as an array since it has to be fed to a method which accepts only a string array.
What I tried so far is:
$sites = DB::select('select site_id from site_tab');
$sites_arr = $sites->toArray();
But this doesn't produce the result I want. I need $sites_arr to be like ['A','B','C',...]
Please suggest a way to get this done. A solution based on Eloquent is also OK for me.
Thanks
Try this:
DB::table('site_tab')->pluck('site_id')->toArray();
reference pluck
referen toArray
If you open a manual, you will see that
The select method will always return an array of results
So, there's no need to use ->toArray(), as result is already an array.
To get values as array of names you can do:
$site_ids = DB::table('site_tab')->pluck('site_id');
Using ->toArray() here is optional, as you can iterate over $site_ids (which is a Collection) with a foreach too.
i'm relatively new to coding and I need a little help. I'm basically trying to loop through an entry in a mySQL database and push any new entry into an array , so that it only comes up once in my array.
// SQL query
$response = $bdd->query('SELECT serie_bd FROM inventaire_bd');
//creating array to group all elements from the db so that they do not repeat
$serie_bd_groupe=array();
while($data_collected = $response->fetch())
{
if(array_key_exists($data_collected,$serie_bd_groupe)==false)
{
array_push($data_collected,$serie_bd_groupe);
}
}
Will this work? - it seems like the loop will just stay stuck after it comes accross an entry a second time because the if statement wont execute itself.
Also in the future, are their any php equivalent to jsfiddle.net so i can test code syntaxically?
Thank you for your time
Your array keys will be default integers, so you don't want to check those. Instead of this:
if(array_key_exists($data_collected,$serie_bd_groupe)==false)
you should do this:
if(!(in_array($data_collected,$serie_bd_groupe)))
http://php.net/manual/en/function.in-array.php
On the other hand, if you're expecting your collected data to be the array key rather than value, you'd do something like this, instead of your array_push:
$serie_bd_groupe[$data_collected] = 1;
then your key check would work.
If you are looking for UNIQUE values (serie_bd) from your database, update your query to include "DISTINCT" like this:
$bdd->query('SELECT DISTINCT serie_bd FROM inventaire_bd');
On the other hand, I think you are looking for http://phpfiddle.org/
I have table of dogs in my DB and I want to retrieve N latest added dogs.
Only way that I found is something like this:
Dogs:all()->where(time, <=, another_time);
Is there another way how to do it? For example something like this Dogs:latest(5);
Thank you very much for any help :)
You may try something like this:
$dogs = Dogs::orderBy('id', 'desc')->take(5)->get();
Use orderBy with Descending order and take the first n numbers of records.
Update (Since the latest method has been added):
$dogs = Dogs::latest()->take(5)->get();
My solution for cleanliness is:
Dogs::latest()->take(5)->get();
It's the same as other answers, just with using built-in methods to handle common practices.
Dogs::orderBy('created_at','desc')->take(5)->get();
You can pass a negative integer n to take the last n elements.
Dogs::all()->take(-5)
This is good because you don't use orderBy which is bad when you have a big table.
You may also try like this:
$recentPost = Article::orderBy('id', 'desc')->limit(5)->get();
It's working fine for me in Laravel 5.6
I use it this way, as I find it cleaner:
$covidUpdate = COVIDUpdate::latest()->take(25)->get();
Ive come up with a solution that helps me achieve the same result using the array_slice() method. In my code I did array_slice( PickupResults::where('playerID', $this->getPlayerID())->get()->toArray(), -5 ); with -5 I wanted the last 5 results of the query.
The Alpha's solution is very elegant, however sometimes you need to re-sort (ascending order) the results in the database using SQL (to avoid in-memory sorting at the collection level), and an SQL subquery is a good way to achieve this.
It would be nice if Laravel was smart enough to recognise we want to create a subquery if we use the following ideal code...
$dogs = Dogs::orderByDesc('id')->take(5)->orderBy('id')->get();
...but this gets compiled to a single SQL query with conflicting ORDER BY clauses instead of the subquery that is required in this situation.
Creating a subquery in Laravel is unfortunately not simply as easy as the following pseudo-code that would be really nice to use...
$dogs = DB::subQuery(
Dogs::orderByDesc('id')->take(5)
)->orderBy('id');
...but the same result can be achieved using the following code:
$dogs = DB::table('id')->select('*')->fromSub(
Dogs::orderByDesc('id')->take(5)->toBase(),
'sq'
)->orderBy('id');
This generates the required SELECT * FROM (...) AS sq ... sql subquery construct, and the code is reasonably clean in terms of readability.)
Take particular note of the use of the ->toBase() function - which is required because fromSub() doesn't like to work with Eloquent model Eloquent\Builder instances, but seems to require a Query\Builder instance). (See: https://github.com/laravel/framework/issues/35631)
I hope this helps someone else, since I just spent a couple of hours researching how to achieve this myself. (I had a complex SQL query builder expression that needed to be limited to the last few rows in certain situations).
For getting last entry from DB
$variable= Model::orderBy('id', 'DESC')->limit(1)->get();
Imagine a situation where you want to get the latest record of data from the request header that was just inserted into the database:
$noOfFilesUploaded = count( $request->pic );// e.g 4
$model = new Model;
$model->latest()->take($noOfFilesUploaded);
This way your take() helper function gets the number of array data that was just sent via the request.
You can get only ids like so:
$model->latest()->take($noOfFilesUploaded)->puck('id')
use DB;
$dogs = DB::select(DB::raw("SELECT * FROM (SELECT * FROM dogs ORDER BY id DESC LIMIT 10) Var1 ORDER BY id ASC"));
Dogs::latest()->take(1)->first();
this code return the latest record in the collection
Can use this latest():
$dogs = Dogs::latest()->take(5)->get();
If I have a statement that I know will return only one result:
$emp_query = "SELECT * FROM table WHERE id = 'employee_id' LIMIT 1"
Is there any way I can access the result of pg_query($con, $csr_query); as an associative array without using a pg_fetch_assoc and a while loop? A while loop seems unnecessary when I know I'm retrieving only one record. Maybe there is some way in PDO as well, I'm just setting it up this way first because I'm more comfortable with the simple way. Thanks.
Something like pg_fetch_result:
http://www.php.net/manual/en/function.pg-fetch-result.php