I have 3 tables I am trying to join.
user
photographer
gallery
They all share the same identifier column user_id.
When I do a select, there is one record in the user table, one record in the photographer table and currently 5 records in the gallery table.
I would like to retrieve just one row back, but containing the 5 results out of the gallery table.
I tried the following but it returned 5 separate rows.
$this->db->select('*');
$this->db->from('user');
$this->db->join('photographer', 'gallery.user_id = photographer.user_id');
$this->db->join('gallery', 'gallery.user_id = users.id');
Basically, every photographer has a user entry, but they may have multiple images stored in the gallery table.
I only require one result per photographer, but need the 5 images too.
Any ideas? Thanks in advance.
You have 2 options as I see it:
Use 2 queries: one for the tables user and photographer where it will return only one record and the second query to retrieve the images.
Leave the query as it is and list the user + photographer from the first row and loop all the rows to list the images.
Note: I prefer using the first method, although it adds more queries to my application, but this way it's very clear what I have intended and other programmers will find it easier to modify my script.
Related
I found that laravel 'pluck' return an plain array and 'select' return an object. Can anyone explain it to me have any other different between two this?
thank you.
Pluck is a Laravel Collections method used to extract certain values from the collection. You might often want to extract certain data from the collection i.e Eloquent collection.
While Select is a normal selection of either multi or specific columns. They are
By using Pluck you only ask to return necessary fields, but with get you will pull all columns. Also select does the same & the difference here is between the returning result. Using pluck cause returning the final result as an array with pair of given arguments, but select return an array (or object) which every single child contain one row.
$name = DB::table('users')->where('name', 'John')->pluck('name');
Select
EX : DB::table('users')->select('id', 'name', 'email)
Select is a method sent to the database that Laravel will translate as
SELECT id, name, email FROM users
This will select the data of the columns you asked and nothing else. It allows you to be more efficient with your request by only asking the required data. Take the example above and image that the user is a Facebook user. It has a ton of data on it, plus relations to other tables. If you just want to display the name, email and a link to the user profile, doing this request!
For more info and knowing more about the expected response visit : https://laravel.com/docs/9.x/queries#select-statements
Pluck
EX:
$users = DB::table('users')->where('roles', '=', 'admin')
$emails = $users->pluck('email')
The Pluck method retrieves the values in a collection that you already got from the Database and that is now a Laravel Collection. This allows you to create an array of the plucked data, but will not improve the performance of your request, as in the Example above, the $users would hold all data of all the admin users.
Since it does not improve performance, what good is it then ?
The pluck would be useful for example to separate some datas in different variables depending on where. You might need the users data for some stuffs, but also want to display a quick list of all emails together.
For more info about the pluck method and understand how to create a keyed array from a second column, visit the docs here: https://laravel.com/docs/9.x/collections#method-pluck
Pluck function normally used to pull a single column from the collection or with 2 columns as key, value pairs, which is always be a single dimension array.
Select will return all of the columns you specified for an entity in a 2 dimensional array, like array of selected values in an array.
Note: Pluck function is a collection function which happens after the data is fetched. Select is a query builder function that builds query to perform in the database server.
Actually select is used inside DB queries, which can affect the performance by limiting the pulled columns. However, Pluck is Laravel Collection's method, so you can use pluck after you pull the data from DB.
new to laravel.
My use case:
Update multiple rows (say: resources table).
Create multiple users (users table).
Retrieve ids of created users
What I currently did:
First, Update the resources table whereIn('id', [1,2,3,4]). (Update eloquent)
Second, Get array of the updated resources (Another eloquent: Resource::whereIn('id', [1,2,3,4])->get()->toArray())
Bulk create a users. Refers to the resources collection above. (Another eloquent: User::create($resources))
Lastly, get the ids of the created users (Not resolved yet. But I might have to use another eloquent query)
All in all, there are 4 Eloquent queries, which I want to avoid, because this might have performance issue.
What I wanted to do is that, On first step(Update), I should be able to get a collection of models of the affected rows (But I can't find any reference on how to achieve this). And then use this collection to create the users, and get the users ids in one query with User::create() so that I will have 2 queries in total.
There is no need to invent performance problems that do not exist.
Update or Insert return only count of affected rows. Commands Select, Insert, Update performed separately. This is a SQL issue, not Laravel.
For single inserts (if you want add one row) you can use insertGetId method of a model.
For example,
$id = User::insertGetId([
'email' => 'john#example.com',
'name' => 'john'
]);
But you get only ID of record. You need to run select to get full data of the row.
To save multiple records with one query you can use
DB::table('table_name')->insert($data);
Since this won't be an eloquent method, you should pass all the columns including created_at and updated_at.
I don't know what is the method name for update.
Assume the following two tables (stripped down to this question, assume there is more data on both):
user
id
user_similarity
user_1_id
user_2_id
similarity
I'd like to use user_similarity as a pivot table to construct a list of users that are similar to a given user.
To avoid storing duplicate data on the pivot table, I'd only like one record per user pair, with the lower user ID being stored in the first, and the higher ID in the second column.
Is it possible to set this up without duplicate data records and only a single eloquent relation?
I have two tables request and status_tracker. I want to list the row in top which has only one entry in status tracker.
I have the query in $user=DB::table('request')->select('request.*)->get();
I want to add the order based on status_tracker table. If request_id has count '2' in status_tracker table I want to display in top of the table
$user=DB::table('request')->select('request.*)(order may happened here)->get();
if ID 19,11,15 has 2 count in status_tracker it should display first and rest of them will display below as 19,11,15,18,17,16,14,13,12,10.
Is it possible by order the row based on another table field count in laravel?
You could use 'withCount' which will add a column named {relation}_count and orderBy with that, so try something like this:.
$user = App\Request::withCount('status_tracker')
->orderBy('status_tracker_count', 'desc')
->get();
You can read more about this on official Laravel docs
Note: Your model relationship should be well established in order for this to work, so make sure you have specified the relations between both tables :D
I am an Parse newbie,
I have one class and one row.
Within that row I want to be able to have like a drop down, so it only has about 5 choices. I want these choices to be in another table. This other table is to have the choices and also images.
Images and other tables are easy. I just want a link between the two tables and hopefully some sort of drop down which reads the results from the other table.
Hope anyone can help me.